When creating a filter located on a dashboard that targets all, is there a way to narrow that filter down?

For example, in our data we have some dates that are well out of range due to data quality issues, but they still appear in the drop downs. Is there a way to say, only make available the below dates in the filter?

Another example, If we want to only look at Emergency data, it still provides all the wards for inpatient activity and activity in other hospitals, meaning, to get to just the Emergency wards you have to scroll through everything?

Hope that makes sense.