I don't think Sophie/Sophia would sound strange with an Irish last name at all. I prefer
Sophia, and you could always use
Sophie as a nn.
Of the two I like
Sophia best, but
Tessa is very pretty as well. Considering your other daughter's names I'd say
Tessa would fit the sib set best, since Sophia/Sophie and
Sienna have sort of a similar sound, so I pick
Tessa:)
♥Leona♥Do you believe?