Stock/Inventory Management

This is a slight misstatement. In the situation described, partners will appear under the Members type when creating an expense claim, not Expense Claim Payers. The results will be as stated. The Guide referred to is below:

The Guide also explains how and why you might set things up so partners were in more than one category.

But I disagree in general with the advice to record withdrawal of inventory for personal use via an expense claim. Expense claims record payment of company expenses from private funds. These circumstances do not involve any payment. A straight journal entry seems more appropriate.