If you want to make a heterogenouos welding, where at least one base metal is stainless steel, always use the Schaeffler diagramm. My first guess would be a high alloyed filler metal, for example Citochromax-R (this is Oerlikon), with Cr18%, Ni9% and Mn6%. This would give you almost for sure an austenitic weld, so very likely no cracks would appear. On the other hand you must check the mechanical properties of this filler metal to the base metals. If it doesn't have enough Rp02, then you should choose something higher, like Cr20%, Ni12%, Mn6% or even higher. These are from Esab, code OK. Good luck. Bye!