TrioM Combine & Merge Orders

We use this app, however, be very careful with settings. As far as I can see, the defaults could cost you. Last year we merged several thousand $ worth of orders but it seems the the app created new orders as if it they were additional sales. Shopify then overestimated the 1099 to the IRS—showing elevated sales.
As a sole proprietor or LLC, you'd need to enter the excess as "returns and allowances" or similar in schedule C of your 1040 federal return. Simply stating your actual sales would underreport sales sent to the IRS and could cost you an audit, and a lot of additional red tape. Depending on your State, the problem could even be further exacerbated.

The app was working great for us for several months. Now we continue to have issues with little care from the support.