Prospective T applied for tenancy and now wants brother to live with him permanently. T has very large income (verified), brother has insufficient income to sustain tenancy on his own. T suggests brother stays there without being made a T.
Reading your article on the Brillouet case, I assume this is a recipe for disaster. Brother will probably be a de facto tenant. Even if a licensee, we would still have to get court order if he refused to leave when asked. And as non-tenant he would not have signed up to the responsibilities of a tenant.
So, if brother becomes joint T (which we prefer to 2 single tenancies), we must decide if we take the risk of T leaving and brother being solely responsible for rent he can’t afford. Correct? (They have a guarantor in another EU country and we can do checks on home ownership/credit ref.)