I have a database (MySQL) and I need data from n databases (probably multiples DBMS). For example, if a person is added as an user in other database i need to update my table with the new name.

The data is critical, and for sure, i only would have access to read.

My database is the only that need to be updated with the new data.

the alternatives that I found:
*Forget all the text above, and simply generate tokens that are distributed to the organizations, that give a token for each user.
*The other sites have (or will build) an API to access the information externally.
*Sync databases (here, i need help about the structure to do that)