"Good morning, are you Vera and Vanya?"
Translation:Доброе утро, вы Вера и Ваня?
I feel like using the short form «добро» should be fine too, but is it just one of those things where it's a phrase that never changes? It's been a few years.
Short forms are only used as predicates. They are also in a quite intricate relationship with the full form, with stylistic complications we only glance over in this course.
This being said, using "добро" is not possible here anyway because it would not be idiomatic even were we to assume it grammatically correct.
Vanya is I guess "informal" or short form of Ivan still вы (which is used for formal) is used in this sentence. Is вы here used for addressing two person (plural)?