Hi advancedlaserrec, 

You can only merge items of the same type. Duplicate service item types can be merged together, but a service type item cannot be merged with a non-inventory item type.When you merge inventory items, QuickBooks merges ALL historical transactions, including the purchases, sales, average costs, etc.

Before attempting to merge your items, make sure to create a backup of your company file. This is in case you need to undo the actions done.

To merge two items:

1. Click Lists > Item List.
2. Review the list for duplicate items; note the name of the item you want to remain.
3. Double-click the item you want to merge into another item. The Edit Item dialog displays.
4. Type in the Item Name/Number field the name exactly as you noted it in step 2.
5. Click OK to save your change. QuickBooks provides a warning message that you are merging items.

Merging items needs careful consideration for this results in a different inventory reduction on all sales transactions, and that means all historical financial statements will be different after your merge. This is definitely something we recommend you consult with your accountant or legal adviser.

Let us know if you have other concerns.
Have a great day!