The question you have to ask is who would be "involved" in giving the opinion. Sure, there could be another person in the room while the doctor is examining the patient and giving their opinion, but really, the opinion is only being asked for and provided by the patient and the doctors.

Forgive me. Could you not argue that they would actually have to shell out money for every child born during the marriage, including those children whose parentage can not be traced back to the two involved in this particular marriage? That seems like the linguistic meaning of that phrase. Just thought this might be fun to think about. IDK.