When I add envelopes to a document, they automatically go to the beginning of a document, not the end. This really screws up page numbering. How can I fix this?
There is no reason why you’d be unable to add anything anywhere. Please edit your question (don’t answer for something which is not an answer) to describe how you “add envelopes”.
But mixing data having fundamentally different semantics in the same document is bad practice (it is like writing about two disjoint topics under the same unrelated title). See my answer to your other question.