mysql database configuring

I have three websites using the same code in PHP. Two shared the same API gateway. The hosting was moved for one of the sites and even though the three sites didnt fully share the database, all are now inoperative. The dababase for one of the sites needs to be reconfigured and inserted into the others. The server will not allow sharing. This is a simple configuration of the mysql databases for 3 websites with about 50 products in each. A single ssl and payment gateway can be used for all.