I'm not for sure I understood your request.
If I did, then:
Backup your data.
Copy the code below to a standard module (if you don't know how, ask).
Run: Run_GetUniqueValues
It was unclear to me whether you wanted a list of all unique values from both columns C & D (or just C).
Thus in the code below you will see both:
For both C & D, remove the apostrophe and add it to the line above.
The function: GetUniqueValues collects unique values from any range and stores it in a string separated by the vbCR character. Then Run_GetUniqueValues puts these values in a string array.
You didn't mention if you wanted these values sorted. I added a Bubble sort function to sort these values.
Then leaving an empty row, I copied these values below the previously last row of data in column C.
Bookmarks