›Can my Verwaltung simply say no?
Only on the grounds in Art. 262 para. 2 OR: undisclosed terms, abusive terms, or major disadvantages. A complete dossier removes the first ground and a well-priced contract the second.
›How much more than my rent may I charge?
Your subtenant may pay for what they actually receive — for example the use of your furniture — but a surcharge that goes beyond that can be treated as abusive. We price it from your actual furnishings and document why.
›Who is responsible if the subtenant causes damage?
You are, towards your landlord. That is why we vet subtenants, take a deposit and record the flat's condition in a handover protocol.
›I am leaving in a few weeks. Is that too late?
Consent should be requested before the subtenant moves in. Get in touch as early as you can; the sooner the dossier is submitted, the more room there is to respond to questions from the Verwaltung.