“if we try to treat her with as much respect as possible, than the answer is easy!
Call her what SHE wants you to call her! “
That, of course, is the absolutely correct and simplest solution. But what if she wants to be called by her first name (yes, I have known such MsIL).
“Well, that’s just lovely. A mother-in-law comparing her daughters-in-law to their faces. No wonder your older sister-in-law can’t “bring herself” to address your MIL as “Mommy!”
I would remind you, LAer. that Mrs. B’s older SIL is the one who will not call their mutual MIL “Mom” and THAT is what led to the MIL’s remark. Clearly the MIL’s feelings are very hurt, and that is not the right way to treat her. Under all other circumstances, I generally agree, in-laws should not voice comparisons of the in-law children to each other, though. We do NOT have one mother or father. Hashem is our first Father, and I am sure she does bnot refrain from davening Avinu, Av Harachaman, just because Hashem is not “her only father.” Our mothers, fathers, and in-laws are ALL extensions of Hashem in that sense. Would she not call her husband’s Bubby and Zaydy by that appellation (if that is how they are known)? After all, they are not “her” B and Z, either! (But yes, they are, once she married into the family).
Although this is very slightly off topic, though in the same ball park, I remember when my daughter-in-law was expecting our grandson, my machetenista was very (and I mean VERY) concerned that only one of us (meaning herself, as she already had other grandchildren) should be known as Bubby and I could be Savta, “because it will confuse the child to have more than one Bubby.” I told her very nicely that though I understood her point, I did not agree with her, and she was free to call herself whatever she desired, but I was more than happy to share the title, because I waited twenty five years to be called Bubby and that is what I would be called. Period. I also politely reminded her that her own mother is referred to as Bubby (not Great-Bubby), and she did not seem to be concerned that THAT would confuse the grandchildren. I also said that the kids would come to know that Bubby usually means “Mommy or Daddy’s mommy who loves us a lot, bakes cookies with us, reads and sings to us on her lap, and gives lots of hugs and kisses.” I have never had a problem.