Then it sounds like you have some kind of Red Sexlink. I'm not sure what the common crosses are in your corner of the world. You could maybe try to find some kind of a hatchery over there and ask them what they cross to make their Red Sexlink.Yes all four came from the same 'chicken man'. He had crates of the brown (buff) girls and crates of the white boys. I know where to find him again but he doesn't speak any English and when I tried my Spanish on him he didn't understand that either! so no hope of him trying to explain what they are to me. Lol. He did ask me if I wanted them for eggs or meat, I told him eggs, so hopefully they will be very productive. They are well over 20 weeks now (not sure exactly) possibly 24 weeks but not a hint of an egg yet, only plastic ones on a couple of the nests.
One thing to remember is that there's two "kinds" of Red Sexlinks (at least this is true in the States). Both crosses make red pullets and white roosters. However one cross (yours) makes red columbian hens and silver columbian roosters (the columbian pattern is the black tail feathers, black primary wing feathers, and small amount of black in the hackle feathers). This cross (in the U.S.) is commonly a Rhode Island Red x Delaware. The other cross makes red hens with white undercolor and white roosters with red shoulders and yellow hackle, saddle, and tail feathers. This cross (in the U.S.) is commonly a Rhode Island Red x Rhode Island White.