I have a 3 way light switch that I want to replace with upb switches.   I only have one extra upb switch lying around.  I used up my last slave switch on another project.  
So my question is if i use a upb master switch in one of the locations do I have to replace the other switch of the 3 way with a upb slave or can i leave the current non upb switch?
Thanks
Todd
				
			So my question is if i use a upb master switch in one of the locations do I have to replace the other switch of the 3 way with a upb slave or can i leave the current non upb switch?
Thanks
Todd