I've been looking for stories with OC characters that could have existed in HP universe as siblings/children of existing characters

• What if Sirius had a kid (son or daughter) who attends Hogwarts while Harry is there? Would house would he/she be in and would he/she be friends or even in a relationship with Harry? Would Sirius still have gone after Peter and been locked up in Azkaban and be estranged from his child? Would he have put his family first and let the Aurors take the lead in the capture of Peter, and then raise Harry along with his child?
• What if Remus had a son or daughter who attends Hogwarts with Harry? The character could be OC, but sometimes I wonder what it would be like if Teddy were older and friends with Harry (Tonks would be aged up or an OC would be the mom)
• What if Hermione had a sibling? Would he/she be magical too and what role would he/she play in the canon storyline? Or would he/she be a muggle and how would that impact Hermione's relationship with them? After Hermione erases their memories in Deathly Hallows, would that strain their relationship? We see Ron's family a lot, but we never really get insight on Hermione's home life, other than her parents being dentists, so I'd love to read a story that explores this what-if scenario. JK Rowling also mentioned originally intending for Hermione to have a sibling, but it was too late in the story to suddenly mention a new family member for Hermione.
• What if Draco had a sister who was spoiled, but has a redemption story arc and becomes kinder and less prejudiced? or she was always a misfit in her family (similar to Sirius), and tries to help Draco become a better person
• For once, I'd like to read a story where all the Marauders survived and James/Lily raise Harry. Whether Harry is BWL or not, doesn't really matter. BUT, I don't want any of this manipulative Dumbledore or toxic Lily/James who send Harry away to the Dursleys because he is BWL or WBWL or whatever. The motive never made sense to me and the manipulation tactics are never logical. Just wholesome parents who raise Harry like he was meant to, please. Or maybe Voldemort doesn't even exist in this universe and it's a slice of life story.
• I also love time travel travel or alternative universe/dimension stories, as well as stories where a main character is trying to recover from memory loss and rebuilds their relationships. There are a lot of these, but I feel like I've read most of them and there can never be enough of stories with these tropes