Active Roles Web UI boolean value default to true

Is there a way in the ARS web ui to set a virtual attribute boolean value to a default?  I have a boolean VA on a web form that isn't populated.  Not all users are created by the sync service, so I need this attribute to default to true, regardless how a user was created.  I would prefer to have the value propagate when the form is opened (even if i have to use a scratch attrib not stored in the db, and retrieve that to put in the va that is stored in the db).