I've started a new game as Navarra, and I've managed to survive the first 10 years without being annexed by Aragon thanks to some provinces I acquired in Italy, alliances with some naval powers, and pure starting luck. I have just lost a war with Aragon, but the terms weren't too bad.
1.) Is it possible (and strategically desirable) to become a junior partner in a PU? And if so, how could I engineer this? It seems to me being a junior PU is better than being a vassal. The way I see it, you get the protection without the need to give money to your master.
2.) Can junior PU/vassals have PU/vassals of their own? For example, say I'm a 2 province Navarre, with 1 OPM Modena vassal. Can I be vassilized with the Modena vassal intact? There's also a chance I will acquire OPM Tuscony in a PU.