I ask because when I try to Load Fallout.Esm, Anchorage.Esm and, BrokeSteel.Esm I get a message telling me Multiple Master Files selected for load. Load operation aborted. What I'm trying to do is change a weapon in anchorage.esm to use the Tesla Cannon Fire animation & Sounds. But some reason G.E.C.K. will not load up more than 2 Esm files at a time.

Just make the following change in your GECKCustom.ini file:

bAllowMultipleMasterLoads=1

Cipscis

Ok cool thanks Cipscis.