Probably different for different carriers, but we do not have the ability to see details of services provided for others in the plan (18+). I can’t see H’s and he can’t see mine. And when the kids were in the policy as adults, I couldn’t see theirs.
For the required preventative care, we each get letters with details of what’s outstanding, and H (the plan owner) gets a separate letter saying that someone is out of compliance with something.
At the time, I insisted on knowing the kids’ login to the compliance site (different from their healthcare portal login) to be able to see who needed to be nagged, and for what. 