How can i form the Polish-Lithuanian Commonwealth?

[Archy]

Hello! I have recently started a campaign as Poland, and i meet all the criterias, except one: ruler also reigns in Lithuania.
From what i've seen, we need to be in a " personal union" , but i have no idea how to do that. Pls help

[ShadoWwolF]

poland actually starts with a decision to automatically get a PU over lithuania in the beginning while you're still in regency. if you missed your chance at that though then you have to get a PU over them somehow. theres a lot of luck involved with that but i think theres a couple personal union guides out there

[Archy]

Well i missed that chance because i was new to the game back then, so now i have to struggle to get it through the game mechanics.

[Driconian]

Don't the Commonwelth is BS that was the biggest mistake I made in my Game get the PU and keep it.

Edit: I should proberlly put why.
I formed the Commonwelth every 3 months I get -1 stab hits
I formed the commonwelth I have has 5 rebelions every month
I formed the commonwelth and as a result wars are bloody awful to fight allways behind in tech slightly I win but geeze its hard.

Been going on for the last 120 in Game years yes Im advanceing but I know for a fact a Pued LIthuania would have aided me more.