"The yandere top father is being teased"?
https://www.mangago.zone/read-manga/stuck_in_my_sister_s_dating_sim/ is it this? Not novel but game tho
Stuck in My Sister's Dating Sim, I think so
This one, its an omegaverse . The premise is that he was reading his sister's omegaverse BL novel with the same name as him and his bestfriend.
https://www.mangago.zone/read-manga/cozy_obsession/
What's that one BL series where the mc got reincarnated into his sister novel or something