Soemone can correct me if I'm wrong, but if you buy a contract with 2023 points banked into 2024, they can't be used until your UY begins for 2024. So if your UY is August or earlier in 2024, then I believe you should be able to replace your 2024 points with the banked 2023 points. This part I'm less confident in, but I think if you borrowed from 2025, those points are now exclusively in 2024 and cannot be returned to 2025, so either way the 2023 points and the borrowed 2025 points have to be used in your 2024 UY.