The wiki's description of the process for forming this nation warns:
(I actually just tried running through that focus to see what the decisions were, since I couldn't find a good list of those. Completed the tree down to the focus, and got no new related decisions at all. So the direct method of discovery didn't work out.)
4 x 50 + 100 = 300 PP. What are the other 300-400 for?the player should save up around 600-700 political power in order to convince the dominions... The player will have two months (60 days) to carry out all five decisions, which cost 50 Political Power to take except for the Discuss Imperial Federation decision which costs 100 Political Power and must be taken last.
(I actually just tried running through that focus to see what the decisions were, since I couldn't find a good list of those. Completed the tree down to the focus, and got no new related decisions at all. So the direct method of discovery didn't work out.)