Replace Values in Multi-select Fields

Replace Values in Multi-select Fields

I have an existing multi-select field and would like to update some of the choices (e.g. replace an existing value with a new one and have all of the contacts that have the existing value selected now have the new value selected).  This seems to be available only on list fields that are NOT multi-select. 

Is this functionality available? If not, when will it be available? 

Thanks,
Becky