In short, yes.

However, I would always advocate having a separate User Account for each user. Modern Operating Systems offer common folders for work that needs to be shared. Do this so you each have your own Windows login, and you can set up a separate Thunderbird profile for each user, and you'll each have your own private workspace too.

If you really don't want to use the facilities offered by your Operating System for support of multiple users, and prefer to share a login, then it's more complicated. You can use Thunderbird's profile manager to create multiple independent profiles, that is, one each for you and your partner. Then if you open Thunderbird via its profile manager, you can select the appropriate profile.

https://support.mozilla.org/en-US/kb/using-multiple-profiles?esab=a&s=multiple+profiles+&r=0&as=s

That's rather clumsy, and I'd want to put in a little more effort and create a link or shortcut for each user that selected the appropriate profile automatically - so this is the "yes" to the question as you posed it.

Thunderbird doesn't share data between profiles easily. My choice for a shared calendar would be to set one up "in the cloud" and have both Thunderbird profiles subscribe to it. Google Calendar is quite straightforward to set up and use. Other calendars, perhaps provided by your ISP or mail provider may work equally well.

More specific guidance on selecting a particular profile:

http://kb.mozillazine.org/Shortcut_to_a_specific_profile

Thanks Zenos, Will give this a try next week. Appreciate the help. The different windows logins is a possibility. Will look at both options.

Thanks!