Sounds like there are 2 types of third party Agreements. I'm sure playing for us would offer him more chances for ones that do not come under the cap compared to playing for some other teams.
From NRL.com
http://www.nrl.com/news/news/newsarticle/tabid/10874/newsid/58360/nrl-salary-cap-explained/default.aspx
Third Party Agreements
Third party agreements are payments made by companies directly to players. There is no restriction on the amount a player can earn through third party agreements where he is being paid for his own intellectual property, without the need to employ club logos or names and where the company involved is neither a club sponsor nor are they acting on behalf of a club to secure the player’s services.
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All third party agreements must be registered and approved beforehand. This is to ensure that they do not become a way for clubs or players to use sponsors or third parties to undermine the salary cap. There are provisions for club sponsors to enter into agreements with elite players and for details see the Marquee Player Allowance section.
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What about money paid from other people or companies?
The basic guide is that if a player is receiving money from any person as a way of inducing him to play for the club, then that money will be included in the Salary Cap.
Income that a player earns from parties not related to his club is generally not included in the Salary Cap, however, the details of the agreement must be advised to the club by the player.
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The club must then get approval for the agreement from the Salary Cap Auditor in order for the remuneration to be excluded.
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In 2006, the NRL also introduced an allowance for players who enter into Third Party Agreements with club sponsors. In 2010, the top 10 players are allowed to earn up to a maximum extra $50,000 each from sponsorship leveraging but the total payments under these sponsorship leveraging agreements must not exceed $150,000 per club.