This might be a lengthy answer, but it will get you what you want...
Imagine if you had one list starting in E3 and going on down, and nothing else is in that column,
And you had a second list starting in G3 and going on down, and nothing else is in that column...
I would combine them into one column and make them dynamic so that the lists could grow and shrink.
( Change to your ranges accordingly )
Put this formula into M3, and copy it on down to row 50. ( This range is for my example ).
It will copy over one list, and when that list runs out it will copy over the next list;
=IF(COUNTA($E:$E,$G:$G)<=COUNTA($M$1:$M2),"",IF(OFFSET($A$1,ROWS($A$1:$A1)+1,4,1,1)=0,OFFSET($A$1,COUNTA($M$1:M2)-COUNTA($E:$E)+2,6,1,1),OFFSET($A$1,ROWS($A$1:$A1)+1,4,1,1)))
Then go to Data Validation in the Data tab, choose " List ", and then for the " source " put this formula into it;
=OFFSET($A$1,2,12,ROWS($M3:$M$50)-COUNTBLANK($M3:$M$50),1)
