How to include product returns into family budget?

[Binyamin Baruch Lowenstein]

Hey guys! I have a budget for how much we're allowed to spend per month (let's say $1000), but I've run into a complication: product returns. Has anyone figured out how to keep track of how much you've spent, and how much you have left to spend? 

I use Personal Capital for budgeting (read: just knowing how much we've spent and made each month and where it went), but even so, our budget only reflects the true amount that we've spent so far once the merchant has processed the return, which can take up to 2 weeks!

So our current budget looks kinda like this: Spent $800 on one card (going to return about $200 worth, though), spent $200 on another card, and the last card has a credit (from returning merch.) of $100. 

How do you do it?