How do I link a client submitted ticket to an internal ticket

How do I link a client submitted ticket to an internal ticket

Currently I have a project that represents our internal ticket queue (only viewable by our company). I would like to allow customers to submit tickets directly but I only want them to see their own tickets (no internal tickets or dialog). Is this possible and how?

I did set up a public project for them and I see they can submit tickets but how can I link those to internal tickets so they are accessible in one project. If this is the wrong way to set this up please let me know.

Thanks!