Can anyone help with my little problem.

I need to find out how to add drop down lists to individual cells. If you
can picture this example......

I have a list with 10 items....in any given cell I would like a control box
a down arrow to select from this list of items....but....I would also like to
drag this box/list down into other cells when new names are added to a main
list.

If this makes sense....all help will be accepted with many thanks.

If it doesnt make sense....sorry.