Fishy Medical Certification

I've got a situation that raises some questions for me about how to handle fishy looking medical certifications, and I'd like your advice. Our policy does not cover this. Here's the situation.

Our EE has just submitted some medical certification forms for a STD situation that is usually routine. However, the paperwork looks fishy -- filled out in different hands, multiple providers with statements that don't entirely mesh, dates for being out of work that are crossed out and written over. Some circumstances around this cause us to be a little cautious, but I don't need to go into those details here. I think our only step here is to fax these to the carrier to begin the claim request. If they have any questions they will contact the physicians noted and take it from there. We did, as a courtesy, send the EE a fairly benign email (I think) saying that it looked like some info was missing, but rather than delay the claim we were forwarding it to the carrier.

But, this has me thinking. We have a paid FMLA leave benefit that is for FMLA situations that might not be covered by our STD insurance. For example, caring for a family member who is ill. We still require a medical certification, but what if we have questions about what is on it, or the veracity of it? What are our rights, and what should we do? Should we require the EE to sign something that allows us to contact the authorizing doctor if we have questions?