We use transform to create bill out of purchase order. As per our requirement we need to bill two purchase orders. So I transformed the POs into two bills and now merging them. If the bill has inventory detail, I am not able to copy/create the inventory assignments for serialized/lot numbered items. It is created properly in one bill but when i try to copy it to another bill, it does not work and fails saying serial number/lot number is required. please help.

There is a system-supported native way that you can combine two purchase orders (assuming they're on the same vendor) into a single bill initially to where you wouldn't have to create two bills and then combined them with code. I'd pursue that first. I think it requires some additional feature (Advanced Receiving?) I can't tell you how to do it via coding, but I know the functionality exists. If you create it as a single bill initially, I'm thinking you wouldn't run into that error.

Oh man, this is a pain! NetSuite gets really weird about serial/lot assignments when you're copying between bills. The issue is that the original bill already "claimed" those serial/lot numbers, so when you try to copy to the second bill, NetSuite thinks you're duplicating them. Try this - on the second bill, manually clear the serial/lot fields first, then re-enter them fresh instead of copying. Or use different serial/lot numbers if you have them available.

sure. Thanks @RJMNS @christianRILECPQ. I'll try these and update here.