I think that there are 2 separate issues:

- Session

and

- Schema

WRT to Session, things get complicated here as you cannot obviously use global session (the one assigned with SQL = statement) for both databases.

This is no showstopper - Sql instances have constructor form with SqlSession as parameter while default Sql constructors are using global session.

Usually one DB is "dominant" for the application. In that case, it makes sense to assign global session for dominant database connection and use constructor with parameter for secondary one.

Now for the schema issue. Obviously, you need two schema files and import each one with its dialect, also duplicate all other details you need.
Simply #undef SCHEMADIALECT after the include and define a new value for it.

I will try to make a reference example for this...

Mirek

#define SCHEMADIALECT <plugin/sqlite3/Sqlite3Schema.h>
#define MODEL <OrionVR/db.sch>
#include <Sql/sch_header.h>

#undef SCHEMADIALECT
#undef MODEL

#define SCHEMADIALECT <MySql/MySqlSchema.h>
#define MODEL <OrionVR/db2.sch>
#include <Sql/sch_header.h>