Our team and expertise

As a dynamic and joyful team, we flexibly combine our skills to develop goal-oriented solutions. Our team brings together people with different backgrounds and capabilities. We collectively speak 18 languages and have spent 90 years living abroad. Our team members move joyn-coop forward in an entrepreneurial spirit.

The entire team is trained in agile project management and regularly participates in customised training sessions, carried out by external and internal specialists, to foster their personal and professional development.

Dr. Christiane Ströh de Martínez

Managing Partner & Senior Consultant

Dr. Christiane Ströh de Martínez is co-founder and managing partner of joyn-coop. She is passionate about truly participatory approaches and creating spaces for deep listening and energetic co-creation within joyn-coop and in other organisations.

Throughout her 15 years in development cooperation, Christiane has evaluated, designed and accompanied development projects across Africa, Asia, Europe, and Latin America. She brings her expertise in participatory methods, co-creation and strategy development to leading change processes, both as a moderator and process facilitator. Her sectoral focus is on inclusive finance, local economic development, inclusive agri-business and sustainable small-scale farming.

Before founding joyn-coop in 2011, Christiane worked as a free-lance consultant in development cooperation and served as a visiting professor at several German universities, teaching a wide range of development-related subjects. In her PhD thesis in economics, she conducted research on inclusive financial sector development and microfinance. She further holds a Diplom degree (master-level equivalent) in International Economics and Latin American studies. Christiane is fluent in German, English, French, Spanish and Portuguese.

Christiane loves to spend time in nature with her family and friends – and bring home fresh leaves for her guinea pigs from her outings.

Christina Kükenshöner

Founding Partner & Senior Consultant

Christina Kükenshöner is co-founder of joyn-coop where she focuses on driving sustainable development with agile approaches.

Christina is very passionate about the Sustainable Development Goals and has made it her mission to assist companies, development finance institutions and foundations to pursue the SDGs in their activities. She has been involved in over 90 projects and has extensive expertise in helping clients with structuring funds and programmes, especially in fragile and complex settings.

Christina is an experienced process facilitator and has trained as an agile coach to assist clients in making their organisations more flexible in adapting to complexities and a rapidly changing environment.

Prior to founding joyn-coop, Christina served as a management consultant at McKinsey & Company and as a senior project manager for Financial Cooperation at KfW Development Bank. She holds a master’s degree from the Harvard Kennedy School.

Christina is a mother of three and enjoys playing the trombone and the piano.

Lina Ghosh

Partner & Senior Consultant

Lina Ghosh is partner and a senior consultant at joyn-coop whose work focuses on organizational and programme development, in particular in contexts of migration, displacement and state fragility.

She has extensive expertise in process facilitation, where she employs agile and participatory methods and adapts them to participants’ organizational ranks, ranging from field workers to top managers. Lina has worked with a variety of organizations, including NGOs and think tanks. She has advised KfW Development Bank, the EU and various UN organizations.

Prior to her work with joyn-coop, Lina supported large private companies in the industrial and insurance sector as a consultant with McKinsey & Co. Thanks to her multicultural background and international study and work experience, she is fluent in German, English, French, Russian and Bengali and has in-depth knowledge of the post-Soviet region and South Asia. Lina holds a master’s degree in International Development and a bachelor’s degree in Social Science from Sciences Po Paris.

Lina has a passion for learning new languages and travelling to unusual destinations.

Corinna Strohbach

Senior Consultant

Corinna Strohbach is a consultant at joyn-coop. She is passionate about financial sector development and combatting climate change.

Her work includes project development as well as conducting conceptual studies and evaluations for key actors in German development cooperation. Corinna is experienced in data analysis and is adept at breaking down complex facts into clear visualizations. Moreover, she enjoys moderating workshops and facilitating processes in diverse cultural settings. Her sectoral focus is on financial sector development, employment promotion and food security/nutrition. Since 2018, Corinna is also a certified trainer for microfinance action learning games.

Before joining joyn-coop, Corinna worked with a regional GIZ project in Asia, supporting the introduction of inclusive insurance. She holds a master’s degree in International Development Studies from Philipps University Marburg and bachelor’s degrees in Economics and Human Geography from Goethe University Frankfurt.

Corinna is enthusiastic about sustainable living and travelling by trains. She enjoys all kinds of racket sports.

Caroline Gruber

Senior Consultant

Caroline Gruber is a consultant at joyn-coop with a focus on francophone Africa. She is passionate about seeing people grow and developing approaches that strengthen their skills.

Caroline’s areas of expertise comprise vocational training, health, livelihoods and rural development, facilitation of Financial Cooperation with NGOs and regional organisations as well as private-public cooperation. In these areas, she conducts feasibility studies, conceptual studies and evaluations. As an integral part of her work, Caroline facilitates workshops and uses participatory methods to enable stakeholders to contribute their insights and perspectives. While her regional focus is on West and North Africa, she has also gained experience in East Africa and Southeast Asia.

Prior to her work at joyn-coop, Caroline worked with GIZ supporting rural livelihoods in central Vietnam. Caroline holds a Master Degree in International Relations from the Political Science Institute of Aix-en-Provence (France) as well as a Master Degree in political science from the University of Freiburg (Germany). She is a German and French native speaker.

Caroline comes from a family of gastronomes and loves to discover new culinary highlights in countries she travels to.

Sarah Stingl-Ellwein


Sarah Stingl-Ellwein joined joyn-coop as a consultant in 2021. She is passionate about urban resilience and systems thinking.

Prior to joining joyn coop Sarah worked at a tech start-up and as research fellow with the University of Groningen. She further completed internships at the European Commission (DG ECHO), the Munich Re Foundation and the Austrian Embassy in Jakarta. Sarah holds a joint Master’s degree in Humanitarian Action (Network on Humanitarian Action, NOHA) from the University of Uppsala and the University of Groningen, with a specialization in disaster analysis and intervention design. Prior to that she completed her undergraduate degree in International Development at the University of Vienna.

Sarah is a native German and Italian speaker, fluent in English and Spanish, and currently working on her French. When she’s not sitting in front of her laptop, she loves escaping to the mountains, travelling to new destinations and playing volleyball.

Ricarda Bollmann

Head of Operations

Ricarda Bollmann is the Head of Operations of joyn-coop. As experienced financial controlling and reporting practitioner, she oversees the finances and internal processes of joyn-coop.

Over the course of her 15-year career, she has lived, studied and worked in Germany, Japan, Hong Kong, South Korea, Singapore and Saudi Arabia. Her work for a variety of companies across the semiconductor and financial services industries has equipped her with extensive knowledge about various accounting and reporting requirements. Ricarda holds an MBA from Heriot-Watts University and an MSc in Area Studies (East Asia) from the University of Duisburg.

Ricarda enjoys her daily walks with her dogs.

Christoph Renken

Partner & Senior Consultant

Christoph Renken is partner and a senior consultant at joyn-coop with ten years of experience in development consultancy.

Christoph’s work is focused on development cooperation in fragile and conflict-affected contexts, as well as refugee and mixed migration settings. He has extensive experience with approaches and procedures of German Financial Cooperation and, inter alia, worked as an implementation consultant for a KfW project in Uganda. Christoph regularly conducts conceptual studies, feasibility studies, peace and conflict assessments, and project evaluations. His passion for innovative approaches has led him to develop a methodology for rapidly selecting and appraising NGO projects, prepare strategic studies on engagement in fragile states, and conduct remote evaluations for inaccessible project areas with the help of online tools and local consultants. Christoph has also designed several funding mechanisms for regional organisations.

Before joining joyn-coop, Christoph worked in a GIZ sector project that advised the German government on transitional development approaches. He holds a magister degree (equivalent to master’s) in political science, law and comparative religious studies from the University of Munich.

Bettina Bauer

Senior Consultant

Bettina Bauer is a senior consultant at joyn-coop. Her enthusiasm for municipal development and conflict prevention has brought her in touch with a range of multisectoral issues and approaches to development cooperation.

Bettina consults on subnational governance and municipal service provision, as well as international cooperation projects in fragile contexts and areas affected by displacement. She further specializes in violence prevention in urban agglomerations, and municipal development adapted to climate change. Her 15 years of experience in development cooperation in numerous African and Asian countries and profound knowledge of a variety of approaches and related procedures make her a valuable partner for finding solutions to challenges related to project management. Beyond studies, thematic assessments and evaluations, Bettina has been the author of numerous hands-on guidelines and issue papers for German Financial Cooperation.

Before joining joyn-coop, Bettina worked as a freelance consultant and served as a visiting lecturer, teaching on the structural characteristics of developing countries and emerging economies. She has also served as a project manager at KfW Entwicklungsbank and holds a master-level degree in Public Policy and Management from the University of Potsdam. Bettina completed her studies with a postgraduate training programme at the German Development Institute. She is fluent in German, French and English.

Bettina is a mother of three, a passionate choir singer, and loves to please others with her homemade cakes.

Nadja Gmelch

Senior Consultant

Nadja Gmelch is a senior consultant at joyn-coop with over 15 years of professional experience. With a strong passion for collaboration, she has been working with diverse stakeholders on the ground in countries such as Haiti, Cameroon, Senegal, and Mozambique. Her areas of expertise encompass capacity development, knowledge transfer, evaluations, conceptual studies, process facilitation, and change management.

Nadja possesses a deep understanding of the education sector and actively engages in multisectoral projects. Her multicultural sensitivities, combined with her open and persuasive communication style, enable her to effectively establish international relationships and networks while bridging cultural divides.

Prior to joining joyn-coop, she worked for different academic institutions, where she designed and implemented development cooperation projects Throughout her life, Nadja has resided in Mexico, Spain, Italy, and Germany, granting her fluency in German, English, Spanish, French, Italian, and Catalan. She holds a Master's (Diplom) degree in International Cultural and Business Studies from the University of Passau, as well as a Master's in European Policies for Development Cooperation from the Autonomous University of Barcelona.

Beyond her professional pursuits, Nadja finds joy in the mountains, indulging in her passion for playing the piano, and embarking on travels with her van and dog.

Prathima Nalabolu


Prathima Nalabolu joined joyn-coop as a consultant in November 2020. She is from India and is passionate about land rights, forest rights, ecological livelihoods, and building climate resilience of indigenous and rural communities. At joyn-coop, she has been working on projects for promoting agroecological approaches, sustainable livelihoods and climate resilience of vulnerable communities, mainly in East Africa and Asia.

Prior to joining the company, she worked for four years as a consultant at the Ministry of Rural Development, India. Her work on facilitating indigenous communities in India to access rights over individual and community land and to develop agriculture and forestry-based value chains has contributed greatly to shaping her ideology and approach. She has a Master’s degrees in Public Policy and in Social Work from the Willy Brandt School of Public Policy and the Tata Institute of Social Sciences respectively.

Prathima speaks English, Hindi and Telugu fluently and conversational German. She enjoys travelling for nature, food and to learn about and from rural and indigenous communities.

Sarah Thoma

Junior Consultant

Sarah Thoma recently joined joyn-coop as a junior consultant. At Maastricht University she completed her BSc in the field of chemistry.

Before coming to joyn-coop, she was working on several sustainability projects within a Dutch company, including sustainable feedstocks, circularity, the SDGs and sustainability reporting. In her most recent project, she used Life Cycle Assessment data to evaluate greenhouse gas emissions across the agricultural value chain. During her previous experiences she learned that big changes can be done more easily than one could think and is excited to contribute to the transition to a more sustainable and just world than we are in today. Sarah is particularly passionate about climate change topics and organizes small academic events on the EU Green Deal in her free time.

She likes doing sports, going on new adventures and biking through Europe during her summer vacation. Sarah is fluent in German, English, French and Dutch and is learning Arabic and Spanish.