...or you can buy a propane tee and tee off at one of the bottles before the RV regulator, then go to the grill with that line.
Google it or look on Amazon, plenty of options for a bottle tee with a hose that screws on like the disposable bottles.
2022 Jayco Pinnacle 32RLTS, Onan 5500, 380 Watts
Solar, GoPower MPPT, Four 6 Volt batteries, EMS-HW50C, Hughes Hardwired Autoformer
2017 Ram Cummins 3500, 4x4, Dually Aisin, 3.73