> I even discover that if firebird embedded would optionally create only
> *one* superserver instance on the first loading into memory - it will be
> a new feature ;)

In General this looks like embedding your application into an firebird
server process

> All other applications will just use fbembed.dll as a client connecting
> to existing embedded instance.

Beware of the case that the first process does terminate before the
others.

> I have in my mind such example: two applications - one which work on
> database using GUI and one which just collect data from external device
> and store in the same database.

If reducing the number of processes involved really is an issue you
could think about embedding the data collectiong application into an
server process.

I would not estimate this to be an issue of general interest, it dies
not make any sense in most cases.

Elmar