Quote Originally Posted by _pAtrIK_ View Post
Hm, what would the FID be in my case?

("F: PID 1, FID 797, Friluftskartan Pro - Svealand
F: PID 1, FID 798, Friluftskartan Pro - Götaland
F: PID 1, FID 1269, Fastighetskartan 2008")
You can try with new Gmaptool to change FIDs in MPS subfile.(Advanced options/Write tag)
I mean :Split by FID the 3 assembled .img, change MPS FID to just one, then Join.