Sum specific values in the Grand Total row of a Pivot Table - excel

Question

Many thanks for your help in advance. I need help finding a way to sum specific values in the Grand Total row of a Pivot Table based on the corresponding column label. The challenge is that the row that the Grand Total is in isn't fixed, meaning in one instance the Grand Total may be in row 9, then after data addition/removal, it will be in a different row. Also, multiple columns match the criteria.
The attached image show what the Pivot Table looks like. I2 and J2 show the output I need regardless of which row the Grand Totals are in.

Answer 1

Credit to #DavidLead for pointing me in the right direction. The three screenshots attached to this answer are a supplement to the guide for using the GETPIVOTDATA formula in excel. I am using Excel 365.
In the first screenshot, you will see the raw data reformatted to have our columns, i.e. Name, B, A, and Month. Cell N2 shows the total/sum for A. in January and the formula is shown in the second screen capture, Cell O2 shows the sum/total for A. for all months combined. The formula is also shown in the second screenshot.
Regardless, you will see in the formulas for N2 and O2 that I reference the cell $G$1. This tells the formula which pivot table to look for the "A.". Then in the third position of the formula, I reference the Pivot field list column name "Month", and in the third position, I specify "January".
The formula can return 1 to 126 pairs of field names and item names that describe the data that you want to retrieve. In my case, I could have retrieved the total for John in January or for all months.
For example,
Total for John in January
=GETPIVOTDATA("A.",$G$1,"Month","January", "Names","John")
Total for John, January thru March
=GETPIVOTDATA("A.",$G$1,"Month","January", "Names","John")+GETPIVOTDATA("A.",$G$1,"Month","February", "Names","John")+GETPIVOTDATA("A.",$G$1,"Month","March", "Names","John")
The benefit of this formula is that if the Grand Total row changes I will always get the sum of A. and/or B. for all months. It is dynamic and is what I needed to accomplish.
Formula Explanation
`=GETPIVOTDATA("A.",$G$1,"Month","January")`
"A." = the column that has the data I need
$G$1 = the reference to the Pivot Table (Microsoft's
knowledge article states this can a reference to any cell, range of
cells, or named range of cells in a PivotTable. This information is
used to determine which PivotTable contains the data that you want to
retrieve.)
"Month" = the column I need
"January" = the name of the row for the total I need
To get the total for "A." from January thru March, I use the following formula:
=GETPIVOTDATA("A.",$G$1,"Month","January")+GETPIVOTDATA("A.",$G$1,"Month","February")+GETPIVOTDATA("A.",$G$1,"Month","March")
The most important factor of this formula is that you reference a cell in your pivot table. In my case, I used $G$1. I also tried other cells in the pivot table as reference cells, and the formula returned the correct values.
I hope this helps the next person who needs a similar solution and finds this answer. Please give this a vote if it helped you.
1st Screenshot
2nd Screenshot
3rd Screenshot