Create new db and keep data syncronized

I have developed a small PHP/MySQL website that allows private-persons or businesses to do their simple inventory. This uses one database. I now want to have one business per database. This means that when a business register on my site, a clone of the dev-database is made and this created business is now attached to this db (mysql-connection has a dynamic field and connects to this users session-database). Tasks 1: Create new company (database) from a php-script. This is pretty easy to do, you can basically write two mysql-calls to do it. But I want to be able to do the following in addition: Task 2, 3 and 4. Task 2. Be able to mange it from a master-admin-area (some /sysadmin/[login to view URL] script or similar area, can use inbuilt password protection), so that I can keep track of all the "installs" done and for instance a) disable, b) delete or c) "upgrade" each install. This admin area can use simple bootstrap. By c) "Upgrade", I mean to syncronize the database against the dev-database that it was cloned from. For instance, I migth add a column of type varchar 255 and this is syncronized to the other databases once I run "Upgrade". I migth also delete a column or change a field length. I have earlier written a "sync" script like this, but I have now lost it and don't want to do it again. It basically dumped the "dev-database" to a text-file and then grabs the columns list from the "cloned database" and compare each of tables and columns with them. If there is changes, columns are added/modified/dropped. MySQL has built in features to list columns and tables. There are a few custom fields named custom_f1_ that should not be deleted or altered. Task 3. Two places in the script, users can upload images/documents. This is directories or links that users may guess or follow link to that I want to avoid out of security concerns. I would want to use for instance a [login to view URL] and [login to view URL] php-file (with session-check from Task 4 below) to be sure that only correct logged in user can see this image. Images/docs are uploaded outside public-document root. You need to write and implement these two [login to view URL] and [login to view URL] (or find another solution to secure this). Task 4. Add session/password protection to the script and complete it (redirect user to login page if not authorized). Basically, make sure a hashed/secret name for db is passed on and check if user is authorized for this db. It uses a common [login to view URL] file, so shouldn't be to hard. It is not so big job to make this work, but it is a bigger job to make it work well and I want that last part.