Thanks, that makes more sense. This is actually pretty much exactly what I do in GoMobile, except we call these 'entity' forms the "Asset Form" associated with an inspection. This basically holds/displays/captures the (mostly) static data about the thing you are inspecting; eg building address, owner details, property id, etc. This model is working quite well for us in the field - every scheduled inspection also downloads the associated asset form, so all the fixed asset data (typically from the council's backend database) is available to the inspector when out in the field, and possible offline.
Indeed, one of the features I'll be implementing is adding the ability to pull in arbitrary asset data into an inspection form (for whatever reason), so I'm acutely interested in how this might be (naturally?) accomplished by being able to reference the asset data associated with an inspection via a suitably identified external instance/XPath query.