I don't think you can do this. A couple of work arounds would be to give warnings as repot headers if the user picked data that was not congruent to the set up (P2 won't work with P1), or create a union table with all of your options then use an if then statement in your select to match back to your 2 variables. For example:
Options:
P1A and P2A
P1A and P2B
P1B and p2B
etc.
then set your select statment:
if parameter= "p1a and p2a" then table1.field=first parameter condition and table2.field= second parameter condition else
if parameter= "p1a and p2b" then table1.field=first parameter condition and table2.field= second parameter condition else if ...