It's hard sometimes to understand what could be going on in their heads but at least you have it safe with a buddy. Pics when you can we love baby pictures.
I sure wouldn't leave it with the mama. Take that one and another and brood them you can try at other times to get mama to accept them but doesn't sound like she is interested now. Usually, the first few days after they have hatched is when they are more receptive to accepting ducklings.
:welcome