Well I’ve never had a ‘pure/cross x pure/cross, In the past it’s been a straightforward ‘bitsa’ crossed with another ‘bitsa’. It is handy to know if the ‘bitsa’ line you want to use breeds ‘true to type’ as is often claimed by their owners otherwise you have know idea what progeny the parents will produce. My current lurcher Meg’ came from collie/grey x collie/grey/whippet and imo turned out physically perfect in shape and form, the space ‘tween ears aint too badly filled either…lol. Her litter mates were all of similar stamp and a second litter from the same parent