Hello @KonradAntczak !
Are you still having trouble with this issue?
What you could do is create a calculated field based on the possible selections that are used in your parameter selection and then assign values. It won’t be exactly the same but it could potentially bring you close to your use case. Something like this:
ifelse(
contains(${Selected Value}, 'a') = TRUE, 1,
contains(${Selected Value}, 'b') = TRUE, 2,
contains(${Selected Value}, 'c') = TRUE, 3,
0)
Let me know if this helps!