Step mommies

Hi girls, the guy I’m with has two daughters under the age of 11. What’s your guys best advice to give another step mom? I’ve been in this relationship for three years now and we are great, but when it comes to his babymommas it’s always something. They always talk crap about me mind you I have done nothing wrong? I help him with the girls and I don’t over step on anyone. I follow his and moms rules but it’s been three years and I don’t know how you step mommies do it 😂😂 this is draining and a bit hard bc they’re not your kids so you can’t speak for neither. Also the way the moms disrespect the dad and keep asking for money aside from the normal agreement financial.

How do I even build my way up with him or a family if the moms always have something to pick about?

How do you guys manage your relationship aside from the bms? Your best advice would be highly appreciated 🙏🏽