She chews a couple of times then sits with her head down. She belches constantly and chews with her mouth open wipes her nose with her hand. We are tired of constantly asking her to sit up,chew,take a bite,use her hankie, close her mouth. Is it wrong if we put her at a table by herself in another room for meals?
Her table manners may not be what they used to be, but that is through no fault of her own. She's mentally not able to recall those manners and reminding her is likely not going to make any difference. I would read here and other places about dementia and the way it causes the person to lose their abilities.
IMO, you need to watch your mom eat so you can determine her competency at it, assuming she passes the swallowing test that is administered by the professional. Manners wouldn't be high on my priority list.
I haven't experienced this, but I can imagine how difficult it is for you and your family. My mom just eats very slowly and that alone drives me nuts when I'm eating with her. Big hugs to you.