Quote B1:21 - The principal purpose of the Squad Declaration System is to ensure that there is transparency and integrity in team selection and that there is no opportunity for those connected with a Club to profit from insider information. Clubs, officials and coaches shall comply with the Squad Declaration System as directed by the RFL from time to time in the match Match Day Operations Manual.
B1:22 - No Super League Club shall name in its 19-man squad for, or play in, any Salary Cap Relevant Match, as defined in the Super League Salary Cap Regulations any Player who does not have a Salary Cap Value of £15,000 or more.'"
Therefore if you wanted to chuck a lot of cheaper academy players in, you would first need to increase their salary.
As for the 19 man squad that is declared then being changed to bring players in late (as happened with Currie and Ratchford) I don't know.
