You could do that, if it was a network calendar with google, outlook.com etc. The network or online calendar could be synced with each profile, or with any device, e.g. phone, that subscribes to the calendar.

There are several add-ons that simplify the setup, depending on the network calendar provider.

If it's a local calendar, I think the only way is to export the calendar from one profile and import it to the other; less convenient than syncing.

I am on a network, I would like to have a co worker able to see and edit my calendar in thunderbird. Is this possible to do? I been trying to look for this and I have not found the solution to my problem. Thank you

The method described above is feasible, but for a corporate network, you would have to ask the administrator if calendars can be set up and accessed by, e.g. CalDAV, by multiple users. Using google, outlook.com etc. is just a simple way to bypass the configuration details of a specific, local network.

You could also add to both profiles the same local .ics file as a "network calendar". In the location point to the local file using the form file:////......