I like the idea of the grey and black or the mother color choices for the front I bet you could do a pretty neat log cabin quilt with black grey and white and then use the colorful fabric for the back. That way everyone would be happy. One side is for the baby that can't see colors anyway and can be used in the bedroom that doesn't clash and then the bright colorful side as the baby grows and can be used in any other room. Then the parents decide which works for them. I think it might be a lovely compromise and make everyone feel valued
