Personal Union issue

Playing as Holland -> Netherlands, I managed to get a nice marriage with Flanders that resulted in them eventually falling into a Personal Union with myself.

They already had two other states as Junior Members and when I took control of the Union as the Senior Member I was put into a position where my Integration was lower than theirs.

I tried to use the Parliament feature, as it was available to use, but once activated, I couldn't pass the measure to adjust my Integration because I am the Senior Member.

I'm guessing that I have to pass Union Laws that lower everyone's Integration and then Pass laws to raise it again to fix the mismatched state I'm in, but I'm currently locked by the Parliament session that can't do anything lol.

If anyone has ran into this and can tell me if my fix idea would work, or if I'm just softlocked from pursuing the Union that would be great.