Touchy subject! Are you friends with the MIL? If so, you might have some insight into how she would feel? And, as mentioned, you also should consider your SIL's feelings. I kind of agree that perhaps it would be good to let her just work on that one for a while, maybe invest in one more foot for it. Then, a little bit down the road, after the dust has settled, so to speak, maybe for a birthday, invest in a new machine for her. Good luck on this one!