> I needed a way to resolve the person the survey "concerns", since currently only the respondent is stored and the relationship to the respondent. 

The original method resolved that; the target of the survey is the participant.  Is there something missing?

> I needed a way to build multiple response sets in the case of multiple children.

I'll look into that one further; I think it should be possible to do that without e.g. building additional persons or participants.