@aquasiox the story does need it though, because her stepdaughter was mistreated prior to "Mildred" being zapped in - as per the Cinderella tradition. The family tensions are necessary, and it also helps to explain some of her bizarre know-how and values that wouldn't have made sense prior.
None of that would've happened if MC weren't isekai'd because some of the ideas she draws upon probably aren't things OG Mildred would've come across even if she died and reincarnated.
As far as useless setups go, I don't think this one's too useless.