You want a cat, a roommate, or a break date. The lease says something else. Your assistant has opinions about enforceability. None of those opinions should leave the house.
Quote the bit you mean
The paragraph, the date the lease ends, the change you are asking for, the date you need a yes or no so you can decide whether to stay.
Assume nothing silently. "We have not added an occupant yet" is a fact. "This is standard" is a guess. Drop the guess.
One ask
May we add a second adult on 1 June, or may we end on 1 June without penalty. Not both, and not a tour of your situation.
They will not open your chat
Write as email. Keep the tone you would use on paper. You approve the note. If the model wrote "as I'm sure you understand," cut it.
If they say no, you have it in a thread. That is useful later. It is not a lawsuit. Do not ask the product to be one.