Re: Marrying a non-muslim who is NOT ready to convert..
If that is the actual purpose, solution is really simple. Dont create problems where none exists. By his family, if you mean his relatives, too bad - this is not about them. If you mean his kids, they will figure things out. 25 years later, things may liighten up a bit, and we all will not have to be in a straighjacket, adhering to customs at the expense of the happiness of whom we love.
Support your brother in the choices he makes - and hope for the best.