Yes, it is. I guess the two problem that caused me to do this was..  

1. I needed a way to resolve the person the survey "concerns", since currently only the respondent is stored and the relationship to the respondent. Do you think I should move this to the derivation step and add an attribute on ImpliedEntity::Survey for the "concerning" person?

 2. I needed a way to build multiple response sets in the case of multiple children.