I thought about asking this on parenting.se but it seemed specialized enough that this site made more sense.
I'm a white man married to a Chinese woman, living in the US. Her parents live in China and are retired (they're about 65yo), and my wife is an only child. Her mother has come over to stay with us twice for long periods to be with and help take care of our son (currently 3yo). She has been immensely helpful both times. Both her parents only speak Mandarin and their regional dialect.
Although there are some (ahem) advantages to not being able to communicate with my in-laws, I've spent considerable time trying to learn Mandarin. It's been frustrating: sometimes I should be able to understand something she's saying (i.e. I know the vocabulary) but can't because her regional accent makes some sounds different from standard. E.g. 'n' and 'l' are the same in her dialect. She can't hear or pronounce the difference between 'snow' and 'slow'. This goes both ways: my pronunciation often isn't good enough for her to distinguish what I'm saying... even though when she finally does get it and repeats it for me, it sounds exactly the same to me (ugh!). So when my wife isn't around (or just as often, gets tired of acting as translator) it would be nice for either of us to be able to write out what we're saying, phonetically.
My mother-in-law's generation didn't learn pinyin. To me it seems fairly easy to learn but that's probably because the Latin alphabet is second-nature to me as a native English speaker. She can associate Chinese characters with phonemes of course, but not with Latin letters (although she can actually identify and say all the letters in the English alphabet).
I've asked my wife about teaching her mom pinyin, but my wife was dismissive and annoyed at the suggestion: usually something like "they're too old to learn". So before I ask my mother-in-law myself if she's interested in learning pinyin so we can communicate better, I wanted to get advice from strangers on the internet. Is it reasonable to try to get her to learn pinyin? Anybody else been in a similar situation?