You can program a macro in the pronto to do the macro as follows:
unit 1
unit 2
unit 3
dim
unit 3
dim (for the brighter one to dim more)

This will choose all the units set to code 1,2, and 3 then dim them together.
The only other way would be to have a controller or use switches with scene modes. Did you purchase Smartlinc switches? If so, you will be able to do some nice scenes with the switches logic like what you want.

Chris Couture