Column dragging with rowspan issue

Hi,

I've got an issue with dragging a column when I have a rowspan set for any of the TD's.
`
1
7
13


2
8
14


9
15
`

Notice how the cell with 9 doesn't stick to it's column but switches into other columns when dragging. And the same goes for other cells within the same row.

Original:

After Drag

The table will be used to create new columns dynamically and some will possibly have customised rowspans so I'm not sure about how to go about doing it