Adding width to shoulders of finished sweater?!

I knit a hooded sweater for my SIL (Not Your Standard issue Sweatshirt, Take Two). I knitted to her measurements, had her try it on at several points in the knitting, finished it, and now she has decided that the neckline is pulled too wide and the shoulders should be an inch or two wider.
I knit it in the round and picked up stitches for the neck edging, sleeves, and hood, and knit them directly on the sweater. The only seam in the whole thing is the shoulder seam. Because of that, I would have to frog over half the sweater to redo the front. :noway:
The only other solution I can think of is to knit a strip that is as long as the armhole and 2 inches wide, then cut the sleeves off and sew this strip to the rest of the sweater using mattress stitch.
Is there any chance at all that this will work? Is there another solution out there? Thanks for any help you can give.

I can’t think of anythng else.

Maybe use a complimentary/contrasting color so it looks like a design feature?

I checked out other “Sweatshirts” on Ravelry and discovered they all had an open neckline, and when I showed them to my SIL, she said not to worry about the shoulders, just lengthen the sleeves a tad. So no tearing apart the sweater!