The nice part about this project is that the top is complete and knowing the size of the girl will result in a dress that will probably fit. Tee tops also means an ease of dressing and a relaxed comfortable outfit.
One can purchase tees of all types, including ready designed ones, cheap ones, those that are too short but still fit well, simple utilitarian tops that can be embellished with appliques, ribbons, pockets. Sewing for a child who lives far away is very difficult as true measurements are hard to take, however, using the tee as basis will most likely result in a dress that will fit well even if fittings are impossible to make while sewing.
I will post my projects over the next few weeks. Hope this idea is of interest.