How do hybrids work?

[bower]

Bower, Thanks. "Charley's June Bug" is dark mahogany, size of golf ball, tomato leafed, not as tasty as "Blackstone's Cherokee."

The mahogany color, if I guess correctly would be red fruit plus green flesh genes. Green flesh (gf) which makes "black" and brown tomatoes is recessive so that would be stable unless there's an unintended cross. With one exception though, it could become a purple-black instead of mahogany brown, if the recessive pink from Black Cherry is still hidden in there.
You probably don't need to worry about the Beta orange turning up, because it is dominant and shows its color even when one allele is present. Beta with gf makes for a yellowish-brown or caramel colored fruit.

[Doffer]

I do not understant the relation between the sft and sp gene?