You should have just sprinkled the top with the sugar. No one would have known the difference since it was hot, it would have melted into the topping.
Don't get all stressed out over perfection, you need to enjoy life (even that puppy) and live it. Perfection is never going to happen in any of our lifetimes. I like your DSIL and I don't even know him, but he knows how to back down stressors. :-)