Iso #1 BOM 1-20
Iso #2 BOM 21-36
ISO #3 BOM 37-42
etc...

all numbering aligning with an exported master BOM may be what he meant?

I know that you can tell the BOM "prompt" to drop at desired number

We do this in Structure:
skid 100s
platform 200s
pipe supports 300
ladder 400
etc...