as i said before adominant trait is passed onto all offspring
And that is wrong. The passing of traits has nothing to do with their respective nature (dominant, co-dominant, or recessive). The passing of the trait is only determined when the sperm meets the egg, and each gives one half of it's genetic material to the offspring.
The Earth is the cradle of mankind, but one cannot live in the cradle forever. -Konstantin Tsiolkovsky