I have a multisite installation and I have created several networks using Networks+.

I need to create some websites in under each network.

Here's my problem:

In a network the database is shared, but I don't want that to happen. I want each website to have each own database.

Is there a tool to split the databases within a network?

And one more question:
Is there a tool to connect the databases of 2 sites sitting on separate networks with one login allowing them to share a common user base?