Interpersonal politics is so hard. I think you're on about it the right way. Maybe bring it up to the cousin. Let her know you see that things aren't the best with certain people but that if she's willing to be friends despite that than that would make you happy. See how that goes.

If being a friend with someone, anyone, is a problem with your MIL, then she has the problem.
If you like her and get along, go for it

Oh go ahead and make a new friend

So you feel like a Hatfield and McCoy situation as if you are being friends with the enemy persay? Because shes from the side of the family where your mom in law has beef. So you dont want to be in the middle? Thats what im getting from you

It’s all family. I think it’s a nice idea!

It's your life... Take what friendship you can

Be her friend

Hmm, I'd say at least give it a try

If they would get mad over that they're pretty strange people

Be her friend

You should be her friend

Go for it

Why not?

If you spoked to your mother in law first and see what she says then maybe

Families are a waste of your life you can’t stay attached to them you got to save yourself ok