are you wanting to ask XYZ member to write a rec for ABC sorority? Because she wont be able to do that...
but, if you want XYZ member to write a rec for XYZ sorority that is perfectly fine. Being open to as many options of sororities is best, so even though XYZ may not be your first choice now, it's still good to get a rec for it as you may end up loving XYZ in the future.