How do I add nulls to this list?

[Alien]

It’s for a drawing issue sheet so I have different series.
In the test above I had 3 drawings in series 20 and 1 drawing in series 68. Series 20 has 3 issue dates, series 68 has only 1 issue date.
I think I asked the wrong question here so have started a new thread here:

Compare one list to another

I have these lists [image] I want to check the data in the right against the one on the left so I get the output: false false << these 3 false for the empty list checked against 1 2 3 false true true << these 3 true for the 1 2 3 checked against 1 2 3 true true false << this output for 1 and 3 checked against 1 2 3 true true << this output for 2 checked against 2 I posted here: How do I add nulls to this list? but after some helpful posts I’ve realis…