They are optional, just saying
Kinda disagree with not going for either Austria or (ideally) Prussia, but it´s a path of no return. Once you DOW either, the goal is reduction to secondary power and Sphering. Else they will annoy you eternally. To cripple Prussia even more in each war, besides taking a state release anything that doesn´t have cores on you, else crisis with Poland will probably be a pain.
The first thing I did was hit Austria with a Liberate Hungary wargoal with Prussian help.
Prussia did nothing.
I basically won that war single handedly. Twas REALLY hard.