It just math formula within context. Put something like;
(Trigger once)
if seed_A.pickedCount equal or greater than 1 >> add 1 to multiplier var
or
if seed_B.pickedCount equal or greater than 1 >> add 1 to multiplier var
or
if seed_C.pickedCount equal or greater than 1 >> add 1 to multiplier var
Score example: (seed_A.Count*50 + seed_B.Count*50 + seed_C.Count*50)*multiplier var
Something like that depend on your formula.