We have multiple sites in our company which are very similar. In all our sites we have an embedded link to a document on another company site. I would like to update the source document and have it automatically updated on all sites so that I don't have to edit each site individually. Is this possible?
Yes, this is possible using the workflow. I believe in all other sites document library has hyperlink type column to display the link, if not create it.
Develop a simple workflow on source site document library /list and trigger this workflow on item creation and updation.
The logic of the workflow action should be update the list item column (hyperlink) for all the sites. So, in this way whenever you update something in the source list, automatically workflow will update in all other sites.