MySQL: Merge Same Database on Several Location into Single Location

I have a registration form, which is exactly the same for several locations. Each of them has a REG column, which is unique for each inserted row. Basically, each data input has a different REG number for it, which is auto incremented. The location's form references a location's table which has the same structure for each individual location. However, we have one central database which pulls all the data from several locations. This central database has the job of manipulating and populate ing all the location's databases. Let's say, I have 3 locations, A, B and C. All those locations are using same database structure to save the data of each individual location. What I need help on here, is how must I change or configure the database table or column so I can "restore" each individual database from the different location's into one single database on the central location. If the structure is same, then the previous data will be replaced by the new one when restore/add to the database in the central location. I have a column called CODE which stored specific hard code for each location, it is just a simple character either A, B or C based on where the location of the database is saved. So, at the specific time, from 3 different locations, the form table will be backed up and sent to the central database. And there, it will be restored or added to the database to populate all from those 3 locations. Any idea and little help, please? Thanks in advance. Here the database layout I would like to be done. And the engine is InnoDB.