I smelt mine by themselves. I cast for a couple guys that shoot BP and they need the softer alloy for their rifles. If a couple slip thru and get melted in with your clip-on WWs it is not going to change the overall hardness of your alloy ( technically it will, but the change in BHN will be negligible). I just make sure there are no clip-ons in with the stick-ons. Good luck!
~NRA LIFE MEMBER~
~NRA CERTIFIED INSTRUCTOR~