Divorced/Remarried with son from previous marriage. Is he covered under my current wife’s health insurance (she’s not his mom).

I'm hoping someone in the health insurance industry can answer a question. I am remarried with an 18 year old son from my previous marriage. My current wife has health insurance through her employer, under which our entire family is covered (we also have an 8 year old son together). While my 18 year old son splits time between my house and his mom's house (my ex-wife), he's now currently in college, about to start his sophomore year living in a dorm. Worth mentioning is that while my 18 year old has his driver's license and official college address as my house, my ex-wife still claims him as a dependent (I don't claim him as a dependent which was part of our divorce arrangement).

So my 18 year old son has been covered under my current wife's health insurance and, to date, it hasn't been an issue whenever we've filed any claims. My question is, technically, is my 18 year old allowed to be under my current wife's health insurance even though she's not officially his mother nor do I/we claim him as a dependent (we file our taxes "married filing jointly"). Thanks in advance for your responses. Just wondering if we're doing something wrong by doing this.

submitted by /u/Biggmoney21