D6Is there a way to filter a merged column and have the filtering options
span 6 seperate columns?

For example, the column header has been entered in a merged cells D1-I1.
The header is the only thing that is merged. Cells D2-D6 each have the value
"planner" written in them. Cells E2-E6 each have the value "design" writting
in them. it continues with F2-F6, G2-G6, H2-H6 and I2-I6. I would like to
filter on the merged cell (D1-I1) and have the values available to be
selected span D2-D6, E2-E6 and F2-F6, G2-G6, H2-H6 and I2-I6.

Please help!