One thing I saw in my current game is if an empire gift you the rest of their empire because their are going to lose a war I create a commonwealth.
The simple way would be to take all the new planets and hundreds of ships in it as you create it!
Now! All planets are to far away from each other. So you have to create many commonwealth or take one planet create a commonwealth and gift them after creation all the other planets and ships.... Very complicate 
But stop what was the names of all the new planets?! I don't know. I have to write it in a peace of paper to find them back in my planet list in diplomacy screen
Oh I forgot to gift one planet or 50 ships to gift my commonwealth... Sorry you have to wait for a couple of turns to be able to trade again with your commonwealth
By the way... Is it possible to fail a crisis? No matter witch choice I take I ever finished the crisis successfully !