Thanks for getting back with the Community, tpmcma.
 

I'd recommend using a group item for what you're trying to achieve. These are container items that include additional items. You can include up to 20 items with one group item. When you pick the item, all of its linked items are added to your invoice and present a subtotal.
 

Here's how to create a group item:
 

1. In the top menu bar, go to Lists, then Item List.
2. Choose Item, then New.
3. Pick Group as its Type.
   
   
    
4. Enter all necessary details.
5. Select Save.

After creating it, you can add it to estimates, then create invoices from those estimates.
 

I've also included a detailed resource about working with group items which may come in handy moving forward: Add, edit, & delete items
 

I'll be here to help if there's any additional questions. Have an awesome Thursday!