I think the op shows her love by caring that her dd does the right thing. The other parent seems to think stealing is fine. I'd lay money on the future of these two girls being completely different.
Op has your dd just started high school? Often in the first year they can suddenly seem a bit show off-ish, same with last year of primary. They are caught in the no man's land of children and teenagers. While we, as adults, view them as children, hormones tell them a different story.
I think you have a few options.
One is taking a draconian method of taking her to and from school, banning the friend, grounding and removal of phone.
Two is filling her time with activities, chores, homework and clubs. This obviously depends on your finances.
Three is a mix of the two, rewarding good behaviour but consequences for the bad.
Volunteering is something she could do, food bank maybe? Church group or a weekend play club where she helps with younger kids. Shopping for elderly neighbours, dog walking etc.
As a last resort you can call social services and ask for help but they are so stretched. Does school have pastoral care? Or any kind of group for troubled children? (By troubled I mean emotionally rather than being in trouble)
As for their dad, this is grossly unfair and I think you need to ask him why they are only having an invite to the evening. Does he see them much? Is their relationship good?
He needs to know what's going on and the role his behaviour could be impacting on her behaviour. The other option is to stop contact which is a last resort but when it leaves your child disturbed then it's not beneficial.