I'm going to be blunt.

The relationship between your children and their mother is none of your business

If she puts one of them in a life threatening situation, you intervene. Until then, stay in your own lane!

Are you people pleasing?

Are you trying to be the favorite parent for self-validating reasons?

Your job isn't to figure out what the relationship between each child and their mother is or will be. Your job is to make sure you don't put any roadblocks between them.

Focus on yourself, your GAL, your core values (man, I'm feeling like a 45 stuck in a bad groove), and how you want to live your life.

Focus on your OWN relationship with yourself and each of your kids, separate from what's going on.

What she gives them as gifts has nothing to do with you.

You aren't going to fix this back to 'normal' and if you keep trying you will certainly make things a helluva lot worse.