I am trying to automate a XY dot chart. My three main variables include:
text, text, and a date. Each of the variables are a list of data in column
form. Everything works correctly now.

My problem is that each day or week, the data is updated...some of which is
still the old data, but now includes new data from the current day/week. I
would like to take two columns of the same data (old version and new version)
and compare them. Rather than manually do this, I would like to automate a
third column that is populated with all the data from the first two lists
without losing any data, also without repeating any data.

thanks in advance for any pointers