Many dreams seem to be status updates of the elementals. Elle (would that actually be Elle "The Body" Macpherson? ) could have been your mental body , and the two sisters suggest that astral and physical-etheric are in close alignment. Sisters suggest a certain similarity of nature while not being the same, as usually you can tell likeness in siblings but still do not consider them all-too similar.

Bridesmaids both hint at similarity (shared "uniform") and also at a possibility of an upcoming union of male and female elements (as marriage is usually seen in energetic terms, a coming together of yin and yang). The similarity to magical photographs in the Potter books could indicate the magical nature of this self-reading, and similarly also denote that it is an ongoing reading, not just a one-shot picture. You're looking at a "live" representation of your energy bodies.

It's very interesting that while one sister is prominent (in that you know her) none is presented as the bride, showing a certain egality among the sisters. This could indicate a good, even balance, that while you're developing your mental body you're not leaving other bodies behind and do not promote one over the other. Elle Macpherson could also represent health/beauty regarding the development of your energy bodies.