Script to combine view fields in the column f(x) function

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In my record form I'm using tabs to break down the record's fields into different project areas. To track each of these project areas I've created identical choice fields that show 8 stages - A to H. This works fine for the record form, and it means that, in the form, I can arrange things by project. On the views, I want to use groups to arrange records by stage. I think it's possible to use a column's f(x) function to combine my identical choice fields into one column where they can be grouped into As, Bs, Cs and so on. The person who's responsible for stage C can then click the group in that combined column to see all the records, in any project, that need his/her attention. My problem is I have no idea how to write the script. Can anyone give me a sample to adapt? Thanks!  

Ninox Profile

Sorry it's so long - I'm trying to be clear! 

Ninox Profile

Another way of posing the problem:

Field/Column 1 has values A B C D E F G H

Field/Column 2 has values A B C D E F G H

Field/Column 3 has values A B C D E F G H

I need to create a new Column 4 with values A B C D E F G H - which calls in all records from Columns 1, 2 and 3. Thus, if Column 1 has three A's and Column 2 has five A's, then Column 4 would show all eight.

The problem is that if the same record has an A in Column 1 and an A in Column 2, it can't appear twice in Column 4 (as far as I know). So the script might have to include an expression that checks duplicate values and ignores them. Or maybe that would happen automatically, I don't know. 

Anyway, the manual hints that there might be a solution, but has too little detail to help me write the script.