The missing top button on the waistcoat was bugging me, because obviously the waistcoat wasn't being held together at the top as it should.
So I took the plunge and cut off one of the lower buttons and stitched at the top instead.
First time I've sewn on a button so tiny. It was fiddly, and since the holes in the buttons are so small I figured you couldn't really stitch it over and over as you would in real life. So I took a different route. When I tied the initial knot in the thread I made sure there was a length of free thread after the knot. I then stitched the button on by pushing the needle though the back of the waistcoat into the first hole, then back through the second hole. I just knotted the two ends together a few times on the inside of the waistcoat.
Just as fiddly though was getting the button fastened through the buttonhole!
While I was at it I glued his shirt collar closed as well.