I just searched for mentions of Family Legends and found only one such question for which I duly coined a new tag of family-legend.
That question came from @Fortiter and was Where do I look for a woman who vanished for 17 years?Where do I look for a woman who vanished for 17 years?
By family legend I mean a story/legend that has been passed down to you (most likely) by word of mouth, or perhaps has been written up somewhere, but currently lacks any or sufficient corroborating evidence for you to be confident that it is true.
I think there must be many amazing Family Legends that could either stand up or fall to closer scrutiny, and am hoping that, if/when this answer floats to the top of the list of yet to be undertaken Weekly Topic Challenge suggestions, you will have at least one to ask about.
This answer became Weekly Topic Challenge #2: Weekly Topic Challenge: Let's ask about Family Legends?