I agree with you to the extent that Kinjal seems like she is married more to the Family than toshu. She likes having a joint family around and I think she hasn't moved out yet for two possible reasons. Anu moving out and Toshu being an *ss is still recent, so no track has developed there yet and also because she doesn't really have any issues at shah house yet. In between all this festival stuff they haven't really shown her being burdened with work or taanas for supporting Anu.
I agree that Kinjal hasn't been a great daughter but I don't really think she is bad as such. tbh she has defended Rakhi in earlier episodes and this was the first time (atleast as far as ny memory serves correct me if I'm wrong) where she didn't do that. It's quite possible that rakhi intimidating baa (even though Baa deserves it lol) didn't go down well with Kinjal. It may also be her twisted allegiance to the shahs 😳so who really knows. I also found Anu asking Kinjal not to meet rakhi pretty weird (I tried going back to the epi and never found the clip tho only read it from people here)
Either way I think Cruelty as a ground of divorce would be unrealistic - because it's only granted when there's a real danger to the victims life - so a lot of stuff would have to go down for that. Same with irretrievable breakdown of marriage - it's given in really rare cases. Best course of action for Kinjal would be to have Rakhi pressurize toshu for giving mutual divorce.
I'm sure Nidhi is in a long term role here so I think they may make her Anu's beti to keep her there
6