Intelligent agg with ILANCESTORS

Re-posting my question here because it might be more appropriate than the Planning forum

I have a data form with two sparse dimensions on the row (CC, Product). Groovy determines my edited members for both dims. I need to run an agg on save but would like it to aggregate intelligently so that it only aggregates up the dependent ancestors to optimize performance. Running AGG(CC,Product) is a bit too slow. I tried this but it's not producing a correct aggregate value:

FIX(Budget_Request)
        FIX(@ILANCESTORS(@LIST("CC1","CC2")))
        	@ILANCESTORS(@LIST("Product1","Product2"));
        ENDFIX
        
        FIX(@ILANCESTORS(@LIST("Product1","Product2")));
			@ILANCESTORS(@LIST("CC1","CC2"));
        ENDFIX
ENDFIX