Well, i did it backwards in 2014... used the ex spouse as the joint filing. I don't reckon it'll matter much...neither spouse worked in 2014, so the taxes would have come out the same either way. I figure that's all the IRS really cares about.
But it's good to know about my stepson. I'll not include him in the taxes this year - I'll pick him up on next year's taxes. I appreciate the info!