Is there any way to tell, via the Sky API, if a record is a constituent vs a non-constituent record?

Within the RE UI, there is a button ‘Change to Constituent’ (see attachment). However, prior to when that button is clicked, the SKY API still returns constituent records if I search for a specific ID or via a related email address. I am trying to find if there is a way to distinguish records that are - for lack of a known term - ‘non-constituents’? In integration service that I built, I only want to find/match against true constituent records or if I find a ‘non-constituent’ I want to be able to convert them to a full constituent prior to updating or linking the constituent to subsequent records. Is there any flag or method by which I can distinguish non-constituents from constituents and also to convert a record to a constituent if needed?