Any insight on the below issue which we have facing on our project will be helpf

Any insight on the below issue which we have facing on our project will be helpful. I am working on a bug and during project creation if the user selects a Large Store, Convenience Retail or Drug Value originating channel the selection of project subtype should be an optional (not required) selection. The dropdown selection should not be removed.

Could anyone let me know what could be the logic which I should use so that" Project Subtype"should be optional for Large Store, Convenience Retail or Drug Value originating channel .
We are using an expression rule "prmOrigChanHasProjectSubType" to pick the originating channel from the constant used out in this expression that is PRM_ORIG_CHAN_STORE_LG = Large Store

=if(contains({cons!PRM_ORIG_CHAN_REGION, cons!PRM_ORIG_CHAN_STORE_LG, cons!PRM_ORIG_CHAN_CONV_RETAIL, cons!PRM_ORIG_CHAN_DRUG_VALUE, cons!PRM_ORIG_CHAN_CANADA, cons!PRM_ORIG_CHAN_OTHER}, ri!origChannel), true(), false()).

Then we have used ...

OriginalPostID-119955

OriginalPostID-119955