This can be set up a couple of different ways. Since you're a beginner user, the EASIEST way to do this would be to just make a y/n field called "IsPrimary" and only print out the primary users on your mailing labels, and allow invoices to be made for primary users' accounts. You could have another field linking secondary users to the primary user's account. This might actually make a good TechHelp video.

A more advanced way to do it would be how I have it set up in Access Developer 14. The Easy Access POS system has Group and Person tables. This is so you can have the Group be a company, a family, etc. and then have individual people at that group be stored in the Person table. That involves much more knowledge with regards to table relationships.

I made a TechHelp video out of your question, but I just realized that I totally forgot to read your question and mention you in the video itself. So sorry about that, Kristine. It just takes SO long to edit a video that's already been published and then re-upload it to YouTube. My bad!