I know this is very much a first-world problem so no snarky comments to that effect, please.
All being well we hope to have a few family members here for Christmas. My brother works in the wine industry and it is a bit of a tradition that he gets hold of a nice bottle of champagne for a toast at family celebrations. This year he has excitedly told me that he has got hold of something really special that he sourced in 2020 and has been carefully storing ever since.
My very lovely MIL does not drink wine because it gives her terrible headaches. This is absolutely fine with everyone and honestly nobody gives it a second thought. We always offer her an alternative which she usually accepts but she insists on being given a glass of Champagne along with everyone else and then always tips it down the sink or into a plant pot when she thinks no-one is looking. I saw her do it once and have noticed it every time since. I know this isn't a big deal in the grand scheme of things but the waste really irritates me and I just don't understand why she does it. She would be mortified if I said anything but equally the champagne is a rare and special treat for the rest of us and I do not want to see another glass go to my peace lily. Is there anything kind or diplomatic I can do about this? I have tried offering a mimosa / Buck's Fizz in the past to minimise the waste without success.