ToUserList display in order of formula entry

I'm using the ToUserList function to create the list (user names) of required approvers for specific records.  Ideally I would like the order of those approvers to match the roles listed in an adjacent section of the record.  I wrote the function to have approver 1, approver 2, etc. in the preferred order, however it seems that they are only displayed alphabetically on the form.  Is there a way to change this default?  I've looked and cannot find it.