When you get to a certain level of complexity in your DXP file, you often hit problems with cyclic dependencies between data tables. It would be extremely helpful to be shown where the cycles exist when you are trying to add new relations.
Furthermore, I think that table relations are by default bidirectional, and that exclusively influences cycle determination. If it were directional, then that would eliminate some cycles. I am trying to balance using relations or adding columns to multiple tables within an analysis when I should be able to use relations if directionality is considered.
I know that in the filtering panel you can set directionality - that should still be allowed, and used in the cycle determination. Not hard to do.
I should be able to see which tables are dependent on other tables via relations, as well as the visualizations they feed.
Maybe in the next version of the Data Canvas? :-)