Indonesia’s growing older population and the persistence of intergenerational co-residence highlight the need for context-specific assessment tools. Yet, there remains a gap in published instruments that evaluate these experiences for older adults and their adult children. This study investigated whether valid and context-specific questionnaires could be developed to assess these experiences through expert consensus. An initial pool of 119 items for older adults and 127 items for adult children was generated from in-depth interviews exploring motives for co-residence. The items addressed domains including filial responsibility, family relationships, marital status, financial circumstances and health-related considerations. For older adults, this included relationship quality with family members and housing suitability, while for adult children, it included parent-child relationships and adaptability to health and household conditions. The Delphi method was then used, with experts in family studies and geropsychology evaluating the clarity and relevance of these items across two rounds. The process refined the instruments, in the form of questionnaires, to 84 items for older adults and 82 items for adult children. The resulting instruments are the first context-specific tools designed for assessing intergenerational co-residence in Indonesia, offering a resource for researchers and practitioners to study family living arrangements. © The Author(s) 2026. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-access-at-sage).