This is so sad! I can’t help but wonder if there is an alternate method with less disruption. believe me, I know little of what i am about to suggest, but, sometimes, even a lousy suggestion can alert one to another way to see the problem. What about removing the sleeves and then letting out the underarm seams, inserting a gusset, if needed. I would leave the dress sleeveless for less pull.
fiftydresses 
This is so sad! I can’t help but wonder if there is an alternate method with less disruption. believe me, I know little of what i am about to suggest, but, sometimes, even a lousy suggestion can alert one to another way to see the problem. What about removing the sleeves and then letting out the underarm seams, inserting a gusset, if needed. I would leave the dress sleeveless for less pull.