Hi,
I have a table with multiple product IDs and date columns - I need to sum up the column "Initial" and the column to its right.

The issue is that, the column to the right of "Initial" is dynamic, it changes every month.
How can I dynamically select "Initial" + 1 column to its right, and then sum them up to get the column highlighted in yellow?
I am trying to avoid using Field Number as well as I am not sure if column positions will change.
Thank you!
sample file attached as well