We have a longitudinal study in which participants complete event recordings (text) across different surveys and then those are presented again in later surveys for them to rate. Right now, it is set up so that - for example -

Survey A creates a  contact list of ID (from external source) and text entries Apos and Aneg.

Survey B then uses ID from A to authenticate and then Apos and Aneg as embedded data to present again. Participants also enter new events as Bpos and Bneg (to be used in Survey C). This creates a new contact list of ID and text entries Bpos and Bneg. 

Survey C is then the same as B except using Bpos and Bneg. 

However, if participants do not complete Survey B, they cannot be authenticated to go into Survey C because they do not exist in the B contact list. 

Is there a way to create an overall contact list so that has ID, Apos & Aneg, after Survey A and then ADDS Bpos and Bneg IF they do Survey B so that the ID remains from A to be able to be authenticated for Survey C. 

This is probably more confusing than I mean it to be… basically, participants do not need to do every single survey, but we don’t want to lose them entirely if they miss one. Our current coding would exclude them as soon as they miss one.