The offspring from the White Cap Black/ Self Black Polish Cross should be Black with a few White feathers in the crest.
If there good Legbars,
Offspring from above cross bred to a Legbar Male should give you Barred offspring.
Chris
Crossing Barred with a White Leghorn would give you offspring that is White and may have a Black feather or two.
You need to cross Black Breasted Red with Barred to get a true Crele. You could cross a Brown Red with Barred and get a "Mock" or "Faux" Crele.
Chris