SD x mainland should be labled as SD crosses
SD x with any jamp blood should be represented as Superjamps

Plus its always nice to know the percentage of the crosses such as 50%SD/50% Normal(or like my SuperJamps 50%SD/25%Jamp/25%mainland).

If you cross SD's with mainland retics the offspring will generally be smaller than the normal and bigger than the SD. The size is also somewhat influenced depending which one is the sire/dame (if the dame is the SD stays a bit smaller than the other way around)