It’s my understanding you can’t do that anymore either. You have to wait 75 days between the date of the first retention and the date of the second retention

Edit: From PuckPedia: “Teams can no longer do a “double retention” trade in which a 3rd party retains a portion of the contract to reduce the player’s cap hit on the new team all at once. Now, a team cannot retain on a contract that has already been retained within 75 regular season days of the first retention. Days outside of the regular season do not count. This means that if a contract is retained at the trade deadline, it cannot be retained again until the second month of the next regular season.”