Here is the rules from the Mainland site:
4.8. Players can only play, in the MUPC 2013, for the club with which they were last registered during the
2012 winter season (February – September).
4.8.1 Further having moved club during the 2012 winter season and played in the MUPC during the
2013 competition, the player must remain with that club for the duration of the 2013 winter
season.
4.8.2 Any request for transfer or matters regarding the eligibility of players to transfer will be at
the sole discretion of NZF and made in accordance with NZF Regulations.