AD is the only source available OOTB. You could create a custom app (or search
to see if a 3rd party has done so) to update user  profiles using the SharePoint
Object Model or Web Services.

Can you import  from two AD forest at the same time, then?

Yes, assuming you setup an account with access, and all the appropriate trusts
are in place. In the import  settings you can customize the source of the
profile imports, just set it up there.

I remarked that

And I think it was not the right instruction cbeause when i sent the
document i i didn't remark that Dave Needs to Import users from Other
Domain.

You need to use the API and write some code to do so...