Objective: This research note has both substantive and methodological objectives. It presents an account of undertaking a surface thematic analysis of a data sub-set from a repurposed public engagement written postcard exercise, to consider: (i) the significant non-relationally framed (i.e. factual and not related to the quality of the sibling relationship) information that people across gender and generation think that researchers should know about their siblings, and (ii) the written postcard exercise as a potential research method in family research. Background: Much research on siblings is concerned with outcomes or everyday relational processes. There is less attention to what people themselves regard as significant features of their siblings’ circumstances that is not shaped by researcher agendas and interactions. Method: The research note draws on electronic and hard copy written postcard data, submitted in response to the open prompt "Please tell us about your brothers and sisters", submitted by 795 children and adults. The majority were aged 29-58 and were female. A surface thematic analysis was undertaken to identify the factual, non-relationally framed information provided by postcard writers in a data sub-set in order to identify the issues that they regarded as important. Results: Postcard writers providing factual information about their siblings’ circumstances did so largely in the here-and-now of their siblings' lives. They addressed family form, geographical location, and age at which siblings left home, framing this non-relationally as information about their siblings. Conclusion: The analysis of sibling-provided information that is not relationally framed provides an alternative or additional perspective to both developmental outcomes research and studies of sibling perspectives. The postcard exercise offers possibilities as a data generation method that enables an initial co-production design.