Reply To: Selecting all tables in a story/document at once?

This is my first request and I hope you can help as I have searched everywhere for a script to do this.
I have an Indesign document that is a complicated calendar template
the months are all tables :1 x ROW with either 28,29,30,31 cols.
However, the grid which these above contain many rows (12) and col(37)
If I try any of the selection scripts then these change all the tables in the entire document including the base grid.
So I need to be specific about selection!

I need to select and change the column spacing for the first and last cell for each of the 4 date single rows (28,29,30,31 cols)

Is it possible to select say, tables with 1 row and 28 cols and reassign a col width for the first and last cell?

There are 12 x 7 (84) single rows to change, so a script would be brilliant for this.

Any help would be much appreciated
(BTW I know how to copy/paste/position scripts in Indesign….have performed this at least 30 times today!)
Indesign CC2015 on a Mac