Hello @cjohnsonuk , welcome to the forum.
Embedding redundant parts in a document / diagram is a clever solution to keep the information up to date and to avoid double work. It is also a complex and advanced technique, so you won't find it often in standard office apps.
So I'm sorry, this can't be done with CryptPad. Maybe tell us what product you use to share knowledge. Personally I use wikis for such a task, but this is of course a completely other way (outsourcing often used information to a separate article) and no a "office document" but more a online knowledge system.
Disclaimer:
I am NOT part of the CryptPad team and I do not speak for the CryptPad team. I am a user helping other users. I got moderation user rights for the forum from the CryptPad team to help a bit, because we all are the community, but that's all.