> Below is a classification, and momentally I would need mixture of DB1
> type, that is some data are replicated from a central location, and DB2
> type, where some distant locations have their own data, that they can
> read and write. Of course I would try to find some kind of a general
> solution, where decentralization parameters could be set up, even on
> table level.

I think that the most of replicators for FB (I can be sure only about
Replicator by IBPhoenix) can do what you need.

> E.g.: Costumers are stored centrally, and are replicated to all distant
> locations. On the other hand, Orders are stored locally, and each
> distant location can place a new order to its own database instance. Of
> course a query like SELECT SUM(TOTAL) FROM ORDERS WHERE ORDERDATE...
> issued from the central location should collect data from all distant
> locations.

In this case you must replicate orders from all distant locations
into central database (but not vice versa). Nothing special.
If your database design fit such requirement, the task must be easy.
Everything you need is to read documentation for a replicator and
configure it properly.

SY, SD.