Are my bridesmaids unusually opinionated?

Two of my four bridesmaids (who are sisters, to each other, not mine) are very outspoken when it comes to anything having to do with my wedding. Including, but not limited to, music, food, their hair, makeup, shoes, accessories. They also want to be more included in things: coming to vendor appointments, looking at contracts, etc. What should they expect, what should I expect? How do I handle this? Is this “normal?”