I will 'assume,' at least for now, that you already have relationships between your Main Form table and the two other tables, LI Attachments and LI Addons.
Ordinarily if you were doing something like printing an invoice with line items (only one related table), I would recommend the common practice of printing from a layout based on the line items.
Not knowing anything other than what you've described, including that the related records are limited to 10 each, I would say you could create a print form, based on the Main Form table, that contains two portals showing related records from the other tables.
To answer your question, basically 'yes.' So if the above solution doesn't work, you might consider consolidating (if possible) the two LI tables into one. Each record of the LI table would have some field that indicates whether it is an Attachment or an Addon. Then you would print this report as a list view of the Line Items table -- possibly with summary parts separating the two types of Line Items with headers, subtotals, etc. AND that would allow you to have more than 10 instances of each.
Is this clear?
Awesome thank you Erik,
It makes perfect sense, I will have to re-construct my table design to get everything to work together.
Again thank you for your quick response