@CennoxX
Thank you, that’s a very simple way of achieving what I need, will definitely try this. Only downside is that I want to keep thd Master file as is, to use for comparison with future new music lists. Could make a copy for your procedure, then add the new music to it, for the next new music comparison.
However today I used this procedure, works well, adapted it from the one posted.
With new music file
1-use Edit Sort lines lexicographically Ascending, just for clarity
2-Highlight all lines then use plugins ‘remove Duplicate lines’, as there are always some duplicates
3-open original Master file and new music file for comparison
4-Use compare plus and ‘Compare’
5-Then use Diff Visual Filters… to hide matches
6-Use find unique lines
7-copy all selected visible lines from New Music, paste into a new file, to keep them separate, then copy into the Master file, for comparison with the next New music file.
Hope that makes sense
This gives me a new file with all new music without any duplicates that exist in the Master file