The microlight / SEP division's the issue if this is for an SEP class rating. So far as I'm aware, you can't test for an SEP class rating in a microlight, or vice-versa (although a current SEP class rating should cover them for microlights so long as they hold an EASA licence and have completed differences training or have microlight grandfather rights).
If he owns it outright, there's no problem with any instruction or testing. If he's a joint owner, there's *probably* no problem, but you'll need to wade into the ORSs to check.
If it's for a microlight class rating, and the EV97 has a Type Approved Permit to Fly (checkable on G-INFO) there's no issue whether it's sole or group owned. That particular issue only comes in if it holds an amateur built PtF (which will include all SEP EV97s).
G