My housing authority told me to stop using my own lease entirely

The addendum supersedes your lease on anything it touches, and that is federal, not a Decatur quirk. The parts your lease covers where the addendum is silent are still enforceable, so the document is not worthless, it just has to be drafted around what HUD already locked in.

Pet clauses are the classic trap because HCV rules treat that as a tenant right the addendum protects, so even a signed lease clause loses at a hearing. I had a no-smoking rider thrown out in a similar way in one of my Tennessee properties a few years back.

The thing I have never seen work is trying to get a hearing officer to enforce a pet clause, a guest policy, or really anything behavioral that the addendum does not explicitly back up. They will look at your document like it is a napkin you found in a pocket.

What actually matters at those hearings is the HAP contract, not your lease, so that is the document I would spend my research hours on before you close on anything. The lease you write is mostly for your own psychology unless it is doing something the addendum leaves open, like specifying a late-fee amount or a unit-specific utility responsibility.

Your own lease clauses survive when they fill genuine gaps, things like parking assignments or storage rules or late fee amounts the addendum never touches. I have had those hold up fine in informal hearings in Fresno and Riverside counties going back to 2014. The pet clause that woman lost almost certainly died because of HUD reasonable accommodation rules around ESAs, not because of anything wrong with her lease document, so the addendum was not even the real issue there.