Sorry about that, you did say "found in unity" my mistake.
Omega qouted "United:[adj] involving the joint activity of two or more;"
Exactly. involving two ore more in joint activity. Trinity- three gods in joint activity. Well, actually, you say that they don't do the same thing in that One comes in the flesh and the other does not. So their activity is not even joint activity in that aspect...
Is The Father God? Yes
Is there a God other than the Father who came in the flesh? Yes, the Son.
The Father is a God (1 God). The Son is God (2nd God). The second god is concluded b/c it is not the same God as the Father who is a another God.