Making an other attempt to explain this, as I think I haven't done a good job
in previous posts. (my appologies)

I have a worksheet that containes product lists. Some are related in that
they are part of an assembly, but appear as seperate lines. In the case
where they are a component of a larger assembly column D is blank for that
item. Each assembly has a master line that includes an entry in column D and
also may have a marking in column A (but not always). In the cases where
column D is blank I need to have the value in column A copied from one row
above.

Also, column B contains the qty of each assembly for the master line, and
qty consists of for the component line. I need to have the mater line qty
over write each of the component line qty values. In the cases where column D
is blank I need to have the value in column B copied from one row above.

Need to do this with a macro. I have a bunch of code already in use that
gets the sheet to this point. The processes described above are the last
steps between me and this being done. Any help you can provide would be
greatly appreciated.

Below is an example

What I have now:
ColA ColB ColC ColD
1 Starter Open Type
3 XFMR Dry Type
AAA 4 Panelboard Type B
1 Box
1 Trim
BBB 2 Panelboard Type Q
1 Box
1 Trim
1 Ground Bar

What I need to end up with:
ColA ColB ColC ColD
1 Starter Open Type
3 XFMR Dry Type
AAA 4 Panelboard Type B
AAA 4 Box
AAA 4 Trim
BBB 2 Panelboard Type Q
BBB 2 Box
BBB 2 Trim
BBB 2 Ground Bar

Thanks in advance.