It is 'clever' to offer another IRQ numbers by frontends here?
You can do that, but then you'll always need to assign a IRQ command to the generated DOSBox conf file if a device is configured, making the entire profile "database bigger".
It does depend on the way you allow your users to configure their IRQ.
If they can choose not to add a IRQ command or not. If they can choose such an option, then it is a problem for the users as they tend to believe that when the option "Add IRQ" is off that IRQ 3 is used for serial 4, wich then does not coincide because of the override by the frontend.
If your users can't coose a "Add IRQ" and an IRQ is always added then this is less of a problem.
In my frontend I just warn people that lets say Serial Device 3 has the same IRQ as Serial Device 1.
Most people won't get that warning though as most people seem to stay away from the communication devices.
Erik.