選択せんたくてき夫婦ふうふ別姓べっせいであれば
sentaku teki fūfube' seideareba

Noun
Da Copula

The "-eba" conditional form ("if/when…") of 選択的夫婦別姓

1. If/When selective separate surnames were allowed.; If/When couples could choose separate surnames.

Ba Conditional