If I understand you correctly, you can do the following:
You can create 2 different Relationship Types (aka RelationshipNames in Kentico language) smth like. "RelatedParticipants" and "RelatedOrginizingParicipants". Your current page will have bunch of related pages of these 2 types connected to it.
in the macro on this page you can do something like this: CurrentDocument.RelatedDocuments["RelatedParticipants"].WithAllData
.ApplyTransformation("CMS.Root.MyParticipantsListing")
Create text/xml transfortmation MyParticipantsListing and you get values of the specific fields from "RelatedParticipants" and "RelatedOrginizingParicipants" documents simply using {%FieldName%}
P.S. WithAllData - can be quite slow depending on a number of relations defined .