Bridesmaid dress dilemma

So my wife to be is having 2 adult bridesmaids and 1 child bridesmaid (9 years old but very tall in age 12/13 clothes) we had originally bought 2 maya deluxe dresses for the adults in different styles and wanted a different style in a size 6 for the little BM. However I can't find the same colour in stock anywhere in a 6, so I started looking on JJs house and ordered some swatches to find the best colour match with the adult BM dresses. One colour is a great match but..... yesterday one of our adult BMs told us she is pregnant and will be 6 months pregnant at the wedding. If she doesn't fit in the dress we have already bought her (flares out from under the bust so hopefully it will) but if it doesn't fit and we have to get her a maternity dress the 2 styles they do in maternity don't come in the colour that suits the best. So do I get our younger one in the colour the maternity dress comes in or do I get the colour to match the 2 current adult dresses and then potentially have 3 all slightly different shades? 🤔


I tried asking MIL to be but she said just put the younger one in an ivory dress, however when I spoke to our neice before she wanted to be in the same colour as the adults, and tbh I do think she's too old looking to be in a flowergirl dress.