Consolidation of various sites with various configurations


I have a scenario where I have 3 different sites with 3 different setups.

The 1st site is a single site, the 2nd site is a multisite with about 25 blogs and the 3rd site has both multisite and multidb.

I wish to create a new site with a freshly installed wordpress activated with multisite and multidb. Then migrate all the data and pictures from the 3 sites into the fresh setup above. As far as possible I would like to have the migration seamless to my users by retaining the exact look and feel of each individual website.

Wish to check if a migration of this nature is feasible and if it is, what would be the possible ways to achieve it?