2 forums merged into one, but....
 

Ok. I am considering merging two of my sites forums. One site has Threads: 129,738, Posts: 1,166,685, Members: 142,983 and the other has Threads: 25,932, Posts: 148,579, Members: 31,752 . The smaller of the two is the newer, more current site and the larger is a strong community declining due to a discontinued product.

I use VB and VBadvanced on both currently.

What I want to do is merger the user database and the forums. Make the site a forums look like the original site a (using a forced template) and the site b forums look like site b. The redundant categories will share take on site b's look.

I want the domains for both sites to stay though.

When visiting sitea.com, the vbadvanced still pulls from site a forums and looks like site a still. When visiting siteb.com, it looks like siteb, but pulls from sitea and siteb forums.

basicly, this would be a merging of forums while still making site a think that site a is a stand alone site. The current site a forums would all fit under one sub category of site b's top level.

I hope this is clear. Anyone have ideas, examples, or suggestions?

Ps. They are on same servers...