How to use Groovy to create unique set of multiple chart string values via a single Grid

Hello,

I'm trying to build a Form and Groovy Script that will allow a user to update multiple "Transaction IDs" simultaneously within a Form. The form is built with a specific POV and the grid contains five enter-able cells, some of which act as the Destination values for these transactions. The groovy script will save the data in the "Source" chart strings based on the POV and I also having it saving the "Destination" chart strings based on the values keyed to the grid.

However, the issue I'm running into, is when the Destination values are differing from each other within the same Grid. My groovy script is saving data within intersections that should remain empty. Originally I was having the edited cells save their data within a List in order to populate a FIX statement and update specific Dimension Members to save the data. I think attempted to instead build a grid on the fly and save the data based on the creation of a POV within groovy.