Service Catalog field properties allow for conditions to filter data sources.  However, there is no “Is Not” operator.  Any ideas how we can filter the field data source to exclude records?

In our Service Catalog, we have a form for ERP access.  There are several divisions within our ERP system and several regional security groups that must approve depending upon which divisions are selected. 

We prompt the requester for their Home Region, then display all divisions available within that home region.  We are using a custom object which contains the divisions and their respective regions. On the Division multi-select field properties, we have created a condition where the Division Region is the Home Region the requester selected on the form.

We would also like to display a separate multi-select field with all divisions NOT within the selected Home Region to allow them to select others, which require different levels of approval.  

As mentioned, the Field Properties condition allows me to filter where Region Is the selected Home Region, but there is no “Is Not” operator.  If anyone has any solutions for excluding records based on a previous selection, I would great appreciate your guidance.