Well, I would wait and see how that turns out, if they haven't fought eachother so far. Him jumping on the roof is comical, but I don't see how that proves an alpha personality lol. But the incident where he chest butted with the other roo does indicate that. Perhaps the person who was going to take your one roo would take the chick instead

but anyways I've seen situations where roos got along despite there being too many of them and even despite alpha personalities, but my experiance is not extensive. Mainly I've seen my mother's bantam flock, which had originally 2 alpha type males, one iffy one, and one total submissive, and the two alphas after having a few scuffles and battles eventually called truce and had a pres vice pres relationship I swear, cause they both kept the other roos and hens in check and crowed together and didn't fight eachother, and when alpha roo died the second in command took over. Now the iffy one and him have established the same relationship. Of course these ones were raised as chicks together, and it can be very different when introducing new roos. Though with this one being a chick of one of his hens (though not biologically) it may be different than a totally strange roo being introduced, which usually doesn't go well. But I wish you the best of luck, and more hens!