Can't add Cel lBorders and Division Lines

When you merge cells as you've done here, the merged cells act as a single cell, and that cell's boundaries are shown in the table, the address of the cell is the address of the top left cell of the group that was merged to form the large cell.

Any formatting applied to the merged cell, including cell borders, applies to that whole cell, not to the individual cells that were merged to create it.

If you want the whole Table to be 'gridded', you'll need to avoid merging cells, or place an independent grid, scaled and positioned to match the pre-merge positions of the pre-merge cells. Any changes in scale of the table would then require an adjustment to the independent grid—not the most enjoyable task.

Regards,

Barry

If A is a header column and B is not, they will not merge. They either have to both be header columns or neither be header columns. From your screenshot, the merged cells your question was about were columns G-K and M-N.