Mark,
Over the years I've had the impression that for the most part, partnerships are tough. This is not just with planes but anything else in life.
Don seems to be happy with his arrangements for now so this proves that sometimes it does work but long term someone will die, get divorced, need some money, loose interest or who knows what else and things will change.
Tread lightly my friend, the more partners there are the higher the risk of failure.
By the way, this opinion is only worth what you're paying for it.
Jim
