Just toss them all in the post, the non lead ones will float to the top.
I don't mix anything, I just pour my ingots and call it good. If you need to change your alloy they do it when you put them in your casting pot.
The only thing I add to the WW is a little solder to fill out the bullet a little nicer.
* (Swinging club) Whack! whack! whack! *
Nope, the old nag's still dead .