My daughter is now pregnant and appears to have blood group O negative. I, the mother, have a positive and the father has b negative. How can this be explained? I did have an injection for rhesus d with my first child.

my daughter is pregnant and has blood group O negative. Her father has B negative. and my mother has A positive. daughter now asks how is that possible, is my dad my dad. I did have an injection for rhesus D in my first pregnancy (was weak) How can I best explain it to my daughter. because she may also need a syringe.