First, my current situation:
I have developed and maintain an online client database system for two companies using two different websites/databases. Now the parent organization of these two companies would like for all of their companies to start using the same system.

Instead of creating 15 separate websites with 15 separate databases, what would be my best approach. Eventually, I'll need to be able to access all companies information via an admin account.

Other info:
These are low traffic private websites. Each company has less than 20 employees that will be accessing the database.
Currently running MySQL db with Coldfusion 9 on shared hosting.

Any suggestions appreciated, either general or specific. If I need to supply more info, let me know.

Thanks in advance,