Default value when using relationships between properties?

I'm trying to figure out if when using relationships between custom properties in vCAC if there is a way to select a default value in the second property based on the selection in the first. For example, if I have a custom property called Environment with selectable values like Dev, Test, Stage and then create a relationship on another property like CustSpec ( to use a specific customization specification for that environment) can I have it add a default value to the CustSpec property without the user having to select it? I have created an XML file as described in the documentation and applied it as a ValueExpression on the CustSpec property; it works great if I manually select the available CustSpec value based of selection of my Environment property, but there isn't a default value and for something with a single option that the user doesn't care about, I'd like it to just apply that value to the property.

Here is a short example of the XML:

<?xml version="1.0" encoding="utf-8" standalone="yes"?>

<ArrayOfPropertyValue xmlns:xsi=

"http://www.w3.org/2001/XMLSchema-instance">

<PropertyValue>

<FilterName>Environment</FilterName>

<FilterValue>Development</FilterValue>

<Value>CustSpecName</Value>

</PropertyValue>

</ArrayOfPropertyValue>