Setting a default value to another value from the table.

I'm building a form in a relationManager and I am building a sort of version control where users can't directly edit an existing item, but they have to create a new one. I would like the 'content' field in the new item to default to the 'content' field of the most recent field (under the same parent model) so they can just make their changes and save, but then delete models to rollback to a certain version. I'm having trouble scoping out how to get that default value. (unless somebody has a better suggestion for versioning data like this)

Solution