Make sure the ingots are small enough to fit into your casting pot.
Sometimes the ingots will not fit , then you have to melt them down and cast into smaller ingots.
I process COWW and range scrap and soft scrap lead and cast each alloy into aluminum mini-muffin pans.
When casting I will use an equal number of each in a pot for a 50/50 blend or straight COWW .
If they won't fit your pot , melting and casting into smaller ingots is the easiest way to make them smaller.
Gary