I am doing something similar: I keep 4 families (1 cock and 2 hens each) and breed every 4 years. I hatch 10 -15 chicks from each family and keep one boy and 2 girls only. Next time I breed, boy A will go with girls B, boy B will go with girls C, boy C with girls D and boy D with girls A.
IF YOU BREED SPLASH TO SPLASH, YOU GET PURE SPLASH.
IF YOU BREED SPLASH TO ISABELLA, YOU WILL GET ALL PURE BLUE BIRDS (THEY WILL CARY ONE COPY LAVANDER). THOSE BLUE BIRDS WILL HAVE SOME GOLD LEAKIGE, ESSPECIALY THE BOYS.
Most probably your white roo is Rececive White and hiding barring behind it. That is how he is producing barred chicks with hens of different color than him.
Pea combs are generally small, but when you compare his with the others combs, his is bigger and "redder". The dark reddish feathers on the wings are indicator to, girls wings will be same color as rest of the body. The shiny tail feathers also point for male.
It is a boy and not Marans at all. It has yellow skin. Marans should have white skin.
Most probably it is Dominique. Because of the Rose Comb, which is too big for a girl that age.
Hope you can keep him. Dominiques are the original American breed.