Costuming for any type of group: you want everyone proportionally looking the same. Group costuming is easy when all your dancers are very similar in size and shape. It can get trickier when you have a wide range of sizes and shapes. Specific design details, such as an appliqué, or even the lengths of a skirt can be problematic, if you get these details wrong. If all performers have been successfully dressed in correctly proportioned costumes, you will not zero in on any one person, but you will see the group as a whole, no matter the diversity of their sizes or shapes. This is the look you are striving for!
When working with your desired costume professional, an important question to ask: Is this professional proficient with a wide range of sizes? If you have a diverse size range, you need to consider the answer to this question.