When you're in relationships, you can link the same non-constituent record to multiple constituent records (Ex: Two parents each have their own record and are both linked to the same child, who does not have a record). You can link these non-constituents in relationships to non-constituent participants, but not vice versa. This is problematic for creating tons of duplicates of non-constituents in our database (such as a spouse who goes to a lot of events, or children who attend multiple reunions with their parent). This one way linking is exactly the opposite I find helpful, because we store much more information about a relationship than we do an event attendee. If I link to the participant record it overwrites all the name, address, gender, and date of birth information. 

Please let us link both ways!