Amending wordpress plugin for additional data

Hi, I am looking for someone who is able to edit an existing booking system plugin for wordpress. The bookings system is being used for an occasional child care service, and are using a bookings system called WP-OBS. At present, the system is fully functional, and people are able to make bookings for a session under a parent account. The problem we have, is that a unique account must be created for every client (child), with unique login and password. This is frustrating for parents who need to enter unique ids for every child they have, and having to log in to separate accounts when they want to make multiple bookings. What we would like to do is have a single parent account, with child data stored in an sql table that is linked to a parent sql table. When the parent logs in, and selects a session for a booking, they will be prompted to select a child for the session (pretty much adding another layer of customer information, in the form of a child that is linked to the parent account). While I'd normally chip away at this myself, we're on a tight deadline and need this completed in the next couple of weeks.