Yes it would be pretty easy to make lavender barred rocks using those lavender birds which are about.
Barred rock male on lavender female. Ought to give all black barred offspring, white legs. Breed the offspring together. All things being equal approx 1 in 4 will be lavender, all males will carry at least one barring gene, 1 in 2 males will have 2 barring genes, 1 in 2 females will be barred, 1 in 4 birds will have yellow skin. So 1 in 16 males will be lavender barred with yellow legs; 1 in 32 males will lavender with two barring genes & yellow legs; 1 in 32 females will be lavender, barred & with yellow legs. Repeat, breeding back to top quality barred rocks, & croosing offspring in the next generation until the birds have the correct type. You may choose to breed less & save selecting for yellow legs until later, the frequency of yellow legs (recessive) increases as the birds get bred back to barred rocks.
