Carrying formulas over to new cell when old cell is deleted: possi

Hi,

I've created a Gantt chart in Excel. The date header for the first column
references the start date of the first task, so in the cell H4 is simply
"=D4".

The column headers show days of the week as well as dates (convenient as I
use workday function to arrive at each task's end date).

If someone has a task that starts, say, on a Wednesday, I want them to be
able to columns H and I. However, at the moment this breaks the reference to
cell D4 - and all the other date headers are arrived at by referencing this
cell ("=D4+1”, "=D5+1" etc.).

Is there anyway I can have the formula "=D4" to be carried over to the new
H4 cell (J4 as was) when I delete the current columns H and I?

Thanks

Karl