Pre-bosman, players were mere chattels, bought and sold without their consent.
Since then, whilst the contract is still active, any deal requires three signatures, buyer, seller aner. Agents may be appointed by any party to act on their behalf. Any animosity between agents is irrelevant, if A wont negotiate with B or C that is irrelevant, it is a private matter between club/player and agent, any deal still needs 3 signatures to become legitamate. A contract between player and agent has no relevance to transfer negotiations and may be subject to a seperate injunction/court case. Should that happen, it effectively means any transfer is no longer viable. As a kfa of long standing, the whole Haaland saga is about as far from a City way of doing business as it's possible to get. Admittably we are living in unique times, never seen before, but even so, surely to fuck we walk away, at least for now.....