[spotty4]

I was a bridesmaid at a friends wedding and she chose 5 girls for her wedding party. Like your situation, we were tall, short, skinny, plump. Her solution was to get a 2 piece dress -- skirt + bodice. That way you can mix and match sizes (larger skirt w/ a smaller top or smaller skirt w/ larger top, etc...) While I personally did not like her ultimate choice, it worked out fine to flatter each of us in our own way.

If you'd like a certain color but its too hard to find THE dress for them, then maybe consider allowing each one to wear a dress that flatters them as long as it suits your color requirement.