You can pay attention to what your mother-in-law likes to eat at ordinary times, and then put that dish on two plates, one in front of her mother-in-law and let her turn it over. Yes, you can divide all the dishes into two parts, half for her and half for others.

Try to put chopsticks or spoons on the dishes, so that she can get used to using chopsticks or spoons instead of eating them herself.

If possible, have dinner together.

You can also save some food for yourself, put it on a plate and find a name for yourself. Let them turn over enough on the table. Anyway, they will eat their own private kitchens and will not be polluted.

If it really doesn't work, put some of each dish on your plate before your mother-in-law turns it over.

It's better to be accused of being uneducated than to feel bad.

You can't say that your mother-in-law cooks, but your children can say that grandma will have a headache in the future, others will spoil her mother-in-law, and the baby won't. They will mercilessly point out what their elders did badly: grandma, you are really unsanitary!