I had the sleeve in July 2017 and my first trip back was february 2018 and I had no problem eating a combination of kid meals, sharing meals and ordering appetizers.
At liberty tree I have both ordered the kid pot roast and also shared pot roast with my son - it was no problem and they split it in the kitchen. I shared with my son at Plaza and also they split it in the kitchen. Le Cellier they just brought extra plates, but it was a filet so maybe harder to split. at old BoG before it was fixed price I just ordered mussels, it was no problem. I have shared a regular size (small) pizza with my son at via napoli no problem but we were not on the dining plan. I'm trying to remember where else I shared - my kid is a picky eater so I more likely ate appetizers than share with what he likes. I have a dining report with photos in my signature but I dont't think I ever finsihed it - and I am probably forgetting some stuff. I have had zero trouble eating less at WDW. I don't even explain, just order what I want... the one thing I DO do when ordering a kid meal is tip a little higher than overall percentage would dictate because the server is doing the same work as if I ordered two full meals rather than one.
I have also done plenty of buffets and just basically suck up and pay for the overall experience.