I'm not sure how old your niece is, but I have a chubby daughter. We have a LOT of success at the Deb store. They have a Plus Size section for girls...and carry the same styles as the other section...the clothes are just cut a little wider. Not all Deb stores carry this section in their store, but a lot of them do. Generally, its 1/2 the store regular sizes and 1/2 the store Plus Sizes. Everything from prom dresses, homecoming dresses, to shoes, swimsuits, jeans, shorts, jackets, etc...they carry it. If you have any questions, just PM me. I've dealt with this all her life and she's 14 now. I may have other suggestions for you depending on her age, etc. Good luck!!