This is simple. I overlooked it for as long as I’ve been using Devonthink, so I thought I would post here in case this might spark any ideas.
I’ve generally ignored annotations. I use them very sparingly - or at least I have up until now.
Imagine you’re envious of any of several applications that provide links of different types. One app might have links for parents, children, siblings, and jump or cross references.
Parents are covered by group or tag membership. Siblings are other members of the group or tag. Children are a little tougher. You could make a group for a document requiring a child relationship. Put the document there along with a subgroup for the kids. I’ve done that a time or two. It’s not as bad as it sounds.
You can add links in a document, but that can clutter things up - assuming you can add your reference links to the document. That’s not practical for photos, for example.
Today I discovered how nice it works to put links in annotations.
You may want to create your own template for reference annotations, perhaps with a bulleted list for different kinds of links, make sure to include a link to the document itself. If a search finds an annotation, you’ll want an easy way to click back to the document it annotates.
Control-option-command-O is your friend, too. If the annotation pane is open in the Inspector, that will open the annotation in a window, making editing nicer.
I use a Keyboard Maestro macro to create new Markdown files. That gives me an automatic title line in the document with a link to itself. The reason for that is if I open the document in an external editor, I like a way to get back to it in DT.
Once you’ve got links in an annotation, the See Also window becomes more useful because it will find associations by links in annotations. The famously wonderful Graph View script by Benoît Pointet catches the links, too.
Anyway, it’s simple and obvious. Wish I’d noticed a long time ago.