Gerard123
You say you both fly from separate airfields, how often do you brief? When I was doing my formation phase on a UAS, each flight was briefed before hand covering what the sortie would entail, SOPs, emergencies, fuels etc. It also covered the way we would communicate ie hand signals/radio. It was as much for the instructors as for the students, as their flying backgrounds varied considerably. Although this may not be practical for you, the more often you can brief together the better.
As for flying under another aircraft in a formation change, I'd stick to well out to one side and slightly lower. Removes the possibilty of decending into your mate should the engine give up the ghost.
Cyclone 733
