manual J program

To get rid of the spaces in the drop down populate consecutive cells, such as AA2:AA4 with =G1,=M1 and =O1
Change the source of the named range Exterior to: =Sheet19!$AA$2:$AA$4
Depending on whether or not more columns may be added to Sheet19, you may want to put the list on a separate sheet.
Let us know if you have any questions.