The idea is to group clusters like
I DON'T THINK
NO I DON'T THINK
I DON'T THINK SO
I DON'T THINK THAT
You can join them up in a process like lemmatisation, either so that the smaller clusters get merged as 'lemmas' of a bigger one, or so that the smaller ones end up as 'lemmas'.
In this screenshot, shorter clusters have been merged with longer ones so that A BEARING OF FORTY-FIVE DEGREES relates to several related clusters:
visible by double-clicking the lemmas to show something like this:
How to do it
Choose Edit | Join | Join Clusters in the WordList menu. The process takes quite a time because each cluster has to be compared with all those in the rest of the list; interrupt it if necessary by pressing Suspend.