Hmmm....I'd offer some different ideas. Outcrossing is actually very hard to see through to completion. It takes major dedication, very high numbers, and ruthless on-going culling. There's actually nothing easy there.
If you keep enough breeders and manage your program, keeping strict records, wing-banding, toe-punching, maintaining multiple cocks, you don't need to bring in new blood as long as you began well. With rare breeds, if one is really intending to work with them, one needs to maintain either alone or with other equally long-term committed breeders a large enough program to be self-containing, or one will be forced to bring in other blood which will likely be a step down.
@Shellz: Being the bearer if hard tidings isn't easy, but Malines were a difficult choice for beginning. They are not in the SOP. There is no established bloodlines surrounding them in North America. You won't have a standard to breed to or mentors to support you save this fellow who has them. I totally--100%--applaud your move to settle on one breed, but before you open Pandora's box and lose another season or two,, I'd honestly--politely--but honestly recommend recycling the eggs, and getting an SOP standardized bird. On many levels, Malines are dead end. I know this falls as a disappointment, but in the long-run you're going to find yourself fairly alone with your Malines. There's so much fun community to be had otherwise.
Best,
Joseph