Olddude, sounds like people are double-dealing with you. They don't listen to you, but when something goes wrong, they call you up and want you to fix it. You are the unofficial dad - but only when something goes wrong.

(I seem to have the same role in my family. I don't even get Christmas cards, but when there's trouble, my phone is ringing.)

Next time, tell sis to get the credit card cancelled and deal with the punk.

Tell baby's parent to take Mom to doc to get stitches fixed. It's the parent who allowed the old lady to pick up the baby.

When mom and aunt complain, quietly leave the room. (pretend you need the rest room) They chose to hurt themselves.

In the meantime, hide the car keys.

Keep in mind that your mother may not simply be defiant. It may be that she doesn't understand things or cannot remember. The brain can be a very odd thing sometimes. I only hope she gets better as she recovers.