Mail merge case with secondary custom entity

I have a secondary entity tied to cases where users can enter multiple "items" they used on the case ticket, so a one to many scenario. What I'm trying to figure out is if it's possible to create a table in the mail merge for a case to show those multiple items. I know there is the option on the quotes/orders area, but from my reading and sad attempts I can't seem to create a "table" on my mail merge word document that brings in the items tied to the case.

Is this even possible or do I need to look at third party add-ons to enhance mail merge?

Thanks for your input! (Sage CRM 7.3 sp2.1)

Chris