Okay, you have 9 months, so I would let it go for now and just tell the colour you are looking at and to go try dresses on so you know what they like.
What I did was pick the desiger that had a colour I wanted. So, I loved the Alfred Angelo Tea Rose colour. So, I emailed them the stores near there house that sold the Alfred Angelo and told them to go look for a dress and if they love it, order it in Tea Rose. Well, mine all happened to want to go together and all loved the same dress. Figures.
I think you tell them the desiger of the dress you love, tell them the 2 colours you love and send them to a store near them to pick out the dress they love. Does that make sense?
They will be really happy that they got to pick it out on their own. And you never know, they might love the dress you picked out, but they have to try it on first, before they will know that.