(First) Firstname

Hey Guys,
I know this is a simple question for the experts. I am using the SIF Driver with Identity Manager 3.0. The default filters send over firstname and lastname perfectly. In the U.S., this would be fine for most people. But I live in Brazil and sometimes people here have names that might lool like Maria Theresa Castro Almeida. In a case like this, I need their Firstname for eDirectory to just be Maria and their lastname to be Almeida. So basically, I just want to keep their (first) given name and their (last) surname.

This also presents problems for their usernames because the driver is set up to user first iniatial of firstname and lastname, so in the example above, this username would become MCastro Almeida instead of malmeida.

Can anyone point me in the right direction? Where should these rules be placed? My guess would be in the Command Transformation right? Would the conditions be something like If Operation equal Add or If Operation equal modify? Thanks.