Activate alternative clauses

How can I make an alternative clause that I can then activate using the arrows icon I saw in the demo video?

For the purposes of Assemble Document, the following how-to article should help:

https://help.clausebase.com/kb/how-to-set-clauses-as-each-others-alternatives/

For the purposes of Q&A, the following article should help:

https://help.clausebase.com/kb/types-of-changes/#ch_9

Thank you Tomas!