Dear Monika,
I am divorced as well. If your friend has "certain" information the insurance company should/will be able to give her some information. As for the employer of the ex...that is a little sticky because she isn't the employee.
If she has her ex's soc.number still, the date that the child was taken care of, other dates or situation that the child was at the doctors office as well. By telling the person over the phone that she is the mother and obviously with the information she would be giving him/her would let them know that she is the concerned parent.
I don't know what she is seeking for but by law your ex has to provide info for insurance and your friend should have an insurance card.
I do understand that a lawyer at this time is not a priority but I would contact the lawyer (if she can) that took care of the divorce. Nicely mention it to the secretary etc....to double check her thoughts or questions.
I would still try to get ahold of legal advice of some sort but it doesn't have to be a major situation.
She may want to check with the hospital and ask them how to remove her from the insurance claim and submit everything to the father. That is another direction to go.
Good luck and hope all turns out okay.
Heather