How to modify expression rule without break compatibility

I have an expression rule formatList that takes 1 parameter formatList(markets). Now I want to modify this rule by adding one more parameter param2 { formatList(markets,param2) }. This expression rule is being used in a process model. If I add new parameter in this rule it will cause exception (formatList has 2 parameters, but instead passed 1 parameters) in inflight process model ( process already started and not completed). Is there any way to avoid this exception? do I have to create new expression rule instead of modify existing one?

OriginalPostID-239110