I understand what you are going through. I will be a mother of two daughters soon. But I will not be the biological mother. I will have them through surrogacy. My surrogate even donated her eggs. So my daughters will not have a single quality of me. This makes my heart break too. But I think that these things do not matter if you start loving the child as your own. As long as you love your children like your own, the children will not forget that love. There is no reason to keep this a secret. Children should know. But they should also know that you love them. And that should be enough. Do not stress yourself over these issues. These things do not matter.