Using Ameraucana the offspring would closely resemble Brahmas. They'd keep the pea comb and similar body shape. Some offspring may have a slight beard and less leg feathering. You'd get the blue egg laying genes your after, all offspring should inherit two copies. So you'd only have to refine the Brahma traits in the next couple generations by culling the undesirables. And you'd essentially end up with a bird that looked like a Brahma but layed blue eggs.
