What is the legal term for the principle behind dependant documents in a legal contract?

If you have a contract called “Document C” that is updating and explicitly referring back to a previously signed contract “Document B” which itself is updating an even earlier contract “Document A,” is there a legal term or principle that states all signed documents are required for the contract to be valid?

In other words, if “Document A” cannot be found (the original or copies) does that potentially invalidate B & C if they’re referencing details from A? Is there a term that describes this kind of dependancy? Thanks!