Kreacher has no children, no. Kreacher's children would have had to serve the blood traitor and his brats. Shame. Dishonour. Mistress was right to forbid Kreacher to marry.
No, Dobby is not having children. In truth, Dobby is not sure he wants them. There is so much Dobby wants to do, and he is having trouble finding a wife.
Winky did not need children. She had Master Barty for her child, and cared for him and loved him. Now Mr Crouch is dead and Mrs Crouch is dead and Master Barty is gone and Winky is too sad for babies