As long as you do a BULKCOPY first or at least make sure you copy MSH.9 -> MSH.9 and EVN.1 -> EVN.1 everything will come out fine.
You *MUST* make a variant that matches for all types. Iusually take an ADT_A01 variant and make any segments not used by all messages optional. Then simply copy this message variant to all others; A03, A04, etc.
