Notes guide
Merge tags and fields
You can merge tags and fields without setting anything up first.
Visit any tag and choose either Merge other tags into this one or Merge this tag into.... Visit any field and choose either Merge into this field or Merge this field into....
Before you confirm, the merge dialog describes everything that will be updated.
Aliases
Aliases let you refer to a note by other names. Open a note, choose cmd-k > Show info, and add them under Also known as. The panel talks about names rather than aliases, so that is the wording to look for.
Search, cmd-p, [[, @, and even # for a tag will find notes by their real name or by any alias.
A single link can also show its own words, without adding an alias to the note. Type [[, then the name of the note you want, then |, then the words to show, and pick the note from the list. So typing [[Vellum|my favourite note app and picking Vellum gives you a link that reads my favourite note app.
To change the words on a link that already exists, put your cursor next to it and choose cmd-k > Change the words....
If you want those words to stick as a real name for the note, look under This link for the entry offering to make them one of the note's names. It spells out your words and the note, so it reads something like Make "my favourite note app" one of "Vellum"'s names. The This link section holds a few other useful things too.
Aliases are included in Markdown imports and exports.