I'm playing as Burgundy, trying to form the Netherlands. Utrecht has all the 4 provinces I need but is currently in the HRE. The current plan is to declare war with CB Conquest with Austria and France as allies; France is currently at war, so I'm waiting for the time being.
I'm afraid that an enlarged Brandenburg may call and join the war with a better military than me. However is is rivalled to the Palatinate, currently the Holy Roman Emperor. I'm uncertain that Brandenburg will answer the call of the Emperor while it is its rival.