Nah, Resurrection didn't change anything, the continuities can't be joined in H20 either. There are a few almost-connections between 4-6 and H20 (like Laurie faking her death in a car crash) because originally H20 wasn't going to ignore that middle trilogy, but after a few messy rewrites they decided to erase 4-6 without getting rid of the mention of the car crash and other things that might have connected them.
Yep, they're all owned by different companies.
1, 4 & 5 are owned by Anchor Bay.
2 & 3 are owned by Universal.
6, H20 & Resurrection are owned by Dimension.