Has it been specified who Shira's father is? Is she a first or second cousin? The chances of being Marie's daughter and having the Talmid last name are little which would mean she's either Killian/Tiberius's daughter or that Ben had siblings from whom Shira descends. I incline towards the latter for I doubt Killian would have gotten to have a daughter whatever the hinted romance story is (though it'd be a very interesting plot twist) and Tiberius doesn't seem like a family's guy.
That brings me to another queschon, though, unrelated though it may seem. Do we know Allison Ryder's age?