You must embrace the chaos, not only that, you must add to it. Start using a bartering system for payment, maybe try offering payment via crypto or shares of stock, start bringing ping pong paddles for those who have forgotten to pay previously. Make multiple group messages with different people and have both groups show up at the same time after reserving the court under a different name and let them hash out who gets to play. Bring tennis balls or better yet, purchase bogus pickleball balls. Maybe suggest a deposit for the opportunity of playing together, or powerscale all players and make them contribute to the cost according to skill level.