I was getting an error when I tried to add/modify records of a related table... it was something like: Cannot change record which is required by another table

What I needed to do was, for the field that was related, I had to add the <%if sfk%> <%sfk%> <%end%> (or something similar). For all of the other data input items, I used the same tags as I did for the primary table, which worked fine.

that's pretty much it.