Even if Smokey is the real daddy, the fact is that Bitsy chose Roscoe to be her official mate, so he gets the official daddy privileges.

Single males can be excellent foster parents sometimes, and if your birds breed again you might consider setting him up with a nest of his own and stealing a fertile egg for him to raise. But I'd recommend starting him out with a fake egg to see how good an incubator he is before risking a real egg.