How can you build on an idea without taking its credit?
Name the original contribution and distinguish what you added or changed. Preserve that relationship without volunteering the original contributor for further work.
Make the addition explicit
Adding a recommendation card to a book-exchange idea is a specific extension. Avoid renaming the entire concept as your own or assuming its originator will collect the books.
Preserve versions and voluntary responsibility
Keep the original proposal and additions in shared notes. Confirm attribution and scope before an external presentation. Decide separately what to use and who willingly takes the next action.
A worksheet you can use
Original contribution: __. Addition: __. Source preserved: __. External use: __. Voluntary next action: __.
Must a tiny contribution be formally credited?
A natural acknowledgment of the connection is often enough for ordinary discussion; every sentence need not become a formal procedure.
Evidence and scope
This is collaboration guidance, not a determination of intellectual-property ownership or contractual rights.
IDEO.org discusses group ideation. WKND arrangements are editorial, not endorsed. IDEO.org Design Kit — Brainstorm
Sources and further reading
This collection in Chinese and English · Life possibilities library