This article summarizes a concept that came from my blog reader. This is actually published in a personal Implementation Guide at -- https://johnmoehrke.github.io/RelatedPersonConsent/ . This concept has not been proposed as a formal work item, but I think it would fit nicely in IHE Basic Patient Privacy Consents for Mobile that I have proposed (more on that soon).
This IG focuses on a use-case where the existence of a representative (e.g. guardian) is backed by a rationale and agreement from the Patient. Specifically some cases: