Can US Citizen file for a Spouse's adopted child (Adopted stepchild)?

I don't believe he can, but if he files for you, I think your daughter can also as a derivative beneficiary if she is a minor. I would look to [url=http://www.visajourney.com]VisaJourney - Your US Immigration Community[/url] for info on this. There are a lot of regulations on adoptions and who can claim who as an immediate relative.