Parent elements. Create new elements that are linked to existing ones.

[jegelstaff]

This way, you can edit any one of the connected elements, the parent gets the changes, and all the child elements get the propagated changes, because they are simply read from the parent.

There is some work to do to figure out if absolutely every element property is inherited, or if there are some that are explicit on the child.

Some work towards this here: #276