By putting the signature block into the footer it appears that you want every page signed in triplicate. That seems massively inefficient and requires a lot more pages than are necessary. I would be putting that full signature block in the document body so it only appears once in the document (at the end). If you need every page INITIALLED then you could add a much smaller block into the footer and your page count would be a whole lot less.
The linked text box approach you are asking about makes no sense to me either. Merged table cells are by far the better approach.
- If you don't need to maintain alignment of text in the last column with rows on the left then merge all the cells in the last column prior to use. If you add subsequent rows, just add merge the extra cells each time you add the rows.
- If you do need to maintain alignment with multiple rows, start with the unmerged cells and merge the required rows as required when you are doing your data entry