[Edi]

I've used #selectsite <nbr> without any problems. You just need to remember to use #end after you stop modding a site or you get weirdness.

For example, #selectsite 31 modifies the first one of EA Mictlan's startsites and #selectsite 4 modifies The Swamps of Pythia.

If you make new sites, that may be different when you assign them to a new nation.