How do I partition a hdd with windows on it

I’m trying to partition an hdd with windows (bootcamp) on it into a 425gb partition and a 75gb partition. (macOS is on a different internal ssd.) Disk Utility didn’t let me create a new partition on the windows hdd, I can’t boot into windows (slowness issue) to partition it there, and I can’t split it using GParted (Linux) either. Does anyone know how to do this (maybe using terminal?)?