Several things aren't clear. For instance, what exactly are you trying to do? I think that once you can clearly express what you want, the answer may be fairly simple.

Looks like you want to be able to subtract, automatically, from QOH in the inventory file, anything ordered in an invoice. But I'm not sure. (By the way, how does "Stcklvl" differ from "QOH"?) If so, this can be done thru multiple relationships, but you need to know, exactly, the mechanics of what you want to accomplish.

I am a rookie, so please be patient. I have an inventory file (which is the master file). When the invoice is finalized (the invoice can consist of multiple line items)I want to update the sales history file from the invoice (carbon copy the invoice in to the sales history file) and reduce inventory(QOH)at the same time.

Inventory File

Prod ID

Desc

QOH

Qty Rvcd

Stcklvl

Invoice (Point of Sale)

Prod ID

Desc

QtySold

Price ea.

Discount

Ext Price

SubTtl

Tax

Total

Sales History

Prod ID

Desc

QtySold

Price ea.

Discount

Ext Price

SubTtl

Tax

Total

Thanks in advance,

Brian