Based off of this question. There are 3 characters, Gary, who is grappling Victor, and both are targeted by Thunderwave from Casey.
Gary makes his save, meaning he is not moved by the spell.
Victor fails his save, meaning he IS moved 10ft by the spell.
By most rulings (as seen in the answers to that question), if Victor is moved out of the reach of Gary, the grapple ends.
My question is, can Gary see that Victor failed his save and voluntarily fail his save in order to maintain the grapple? Conversely, can Victor see that Gary made his save and voluntarily fail his own save in order to escape the grapple?
More generally, is there a specific order to saving throws and when can one choose to voluntarily fail?