Dependent Coverage

My wife gave birth to twins 9 weeks early and we need to make sure we get our twins added correctly to a one of our employer sponsored health insurance plan. My wife and I both work, and covered separately by our employer plans. We have a 3rd daughter who is on my work plan.

Since we live in Georgia the twins get 30 days of coverage under my wife’s plan. Her plan would also take precedent for the first 30 days if we added the twins to my plan due to the birthday rule.

It will cost less to add them to my wife’s plan (higher premium, but only one family out of pocket max being reached), but is there any rule/law that would prevent our children from being on different plans?

or do we just add them to both plans (no incremental premium cost to add them to my work plan, and my wife’s coverage would still take precedent, so it should be only her plan’s out of pocket max applying) just to be safe? I’m thinking this is the best option as these NICU bills are going to be over half a million, and want to avoid any insurance company loopholes that would stick us with the bill.