- Registration date
- Sunday September 12, 2010
- Last seen
- January 14, 2021
Not entirely sure I fully understand you.
Let's try a formula first.
This is how I imagined your request:
In column A you have dates. When 12 columns or less contain data, you want to add 14 days to the date in column A and place the new date in column B.
Formula in B2:
When column M contains data, more then 12 columns are used and column B remains empty.