Copy data value to new instance in 1 case, but not in another

I have a table setup to add new instances in different ways.  One adds a single row, one adds the whole table again (with the button for the row added as well).  When I add a new instance of the row I want any data entered in the first cell, to copy to the second row's first cell.  I can achieve this with global data.  I thought this was good.  However when I add the whole table, its copying this data as well (didn't think this through...), and I need my users to be able to enter new data in the second table, and have that 1st cell to copy down in any subsequent rows for the second table.  Correct example below:

Is there a way to do this?  I imagine it will involve scripting - I am still learning how this works, but am willing to try!