I think there might be some confusion about the best friend requirement because there was a stricter requirement in place for the Baby Boomer challenge in 2011? That definitely had a rule that if Sim A claimed, say, Bella Bachelor as their best friend for the challenge requirement, nobody else could even *be* best friends with Bella Bachelor. My understanding is that for purposes of this challenge, the immortals need non-overlapping lists of "claimed" best friends. If you happen to also be best friends with someone on your parent's list, that's okay, you just can't claim that person for your own list.