Thanks, ladies! A lot of these are lovely, just not hitting the spot for me. 
I’m intrigued by Tessalie, and have to admit I quite like it–but is it a real name? I need a legitimate name with meaning and history behind it, I’m afraid. 
I think Tessalie sounds adorable, but I’m not sure I could use it if it was a modern smoosh. I like [name]Tasmin[/name] and [name]Tempest[/name], too, but not enough to use them.
My only other thoughts are [name]Elisabeth[/name] nn [name]Tess[/name] and [name]Beatrix[/name]/[name]Beatrice[/name] nn [name]Tess[/name]–I’ve heard both, but I’m not sure if they’re too out-there. [name]Elisabeth[/name] nn [name]Tess[/name] can work for me, but I really don’t think I’d ever use [name]Elisabeth[/name] if I’d already used [name]Isabelle[/name]…
I’ve come across Edessa/[name]Odessa[/name]/[name]Adessa[/name], and I think that would be perfect for [name]Tess[/name], but I’m not sure I really love it. I have issues with the Nazi connection to [name]Odessa[/name], too…
I think it’d honestly come down to [name]Theresa[/name] or just [name]Tess[/name]…