Help with Marlin TMC Stepper Current Calculation for Series Steppers

Hi All,I'm working on a large 3D printer with abit over a square meter surface area print bed. The design I've settled on moves the printbed up and down while the printing carriage moves above. I've got constant force springs handling much of the weight of the bed while 4 pancake steppers on threaded rods at each corner provide the linear motion. The steppers are all connected in series from one driver chip because I only had one remaining driver free on my 3D printer board. The trouble I've ran into is that during long movements one or several of the steppers will miss a few steps or not turn at all. causing the printbed to become angled. This happened occasionally when there was no load on the steppers at all so I believe this is an issue of a firmware setting regarding the current the driver is delivering. Marlin has a firmware setting regarding Vref/Stepper current however I've found a variety of different ways online to calculate this that all give varying values some of which perform better or worse than others. Can anyone help be find and understand the correct way to calculate for the marlin current setting/stepper software Vref?My 4 motors all in series motors are NEMA 17 1.0A 4.1VMy driver chip for the series is a TMC5160 rated for a maximum current of 4.4AAny help or links to related content are appreciated.