Dear Candy,
You need a couple of people to greet folks as they enter the church. There's a lot of running back and forth. Gifts have to be schlepped to the gift table, people need to know where to put their coats, or locate the restrooms. For a moderate sized wedding, I can see two or three people doing that.
Then, there the actual ceremony. You need a couple of people (usually called ushers) who can assist anyone who needs to leave the room, perhaps for the restroom or to shush a fussy baby. Specifically the usher has to be assertive with parents of unruly children to get them out of the room so the kid can be disciplined, fed, diaper changed, whatever.
I suggest using different people for that. In other words, your pre-ceremony hostesses are off-duty during the ceremony and your ceremony hostesses are off-duty during the entry and seating time.
If you think along those lines, you'll probably have enough jobs to assign to the various people who want to help out.