I very much agree with this. I think it’s great that OP and his ex are on good terms. I’m a stepparent myself, and my SO is also on good terms with his ex. It’s a blessing to have a low conflict arrangement.

However, I would never marry someone with kids under the age of 18 if they didn’t have a court order specifying things like child support and custody. Maybe it’s because I’m a lawyer myself, but I don’t see getting a court order as contentious. You can easily agree to everything and just ask the judge to approve it and sign off on it so it’s official. In my mind, that’s a very small ask. Back child support is a thing, and no matter how great the ex is, I’m not putting any part of my financial well being in her hands.

I put my foot down earlier in my relationship when my SO (who has had unofficial 80% custody for a few years now - court documents actually specify 50/50) thought he could move 5 hours away with the kids without modifying the court order all because “my ex agree I could do it it’s fine.” Fuck no. If she’s willing to agree over text then she can put it in writing on a legal document too before we move 5 hours away.

How I handled it, however, was by offering to pay for the attorneys for both my SO and his ex (for a separate attorney of her choice) to get the paperwork handled.

It’s not hard to get these things done. If it’s all agreed, it usually costs about $2,000. That’s a pretty small amount for peace of mind in my opinion, and there doesn’t have to be anything contentious about it.

Alternatively, the girlfriend can just wait a couple years before mingling assets with OP.