Word. I'm very pleased that Suigintou made a comeback in the series. This puts the series on a new level of badass-ness.

And I think each dream world is connected, via that giant tree you saw in one of the episodes in season 1. So, technically, the father could go into Juns dream as such. Save the fact that he is the Rozen Maiden creator and his powers probably exceed any dolls so far. That includes Suiseiseki and Souseisekis powers to pry open any dream portal.