1. Don't encourage your son and his wife to stay under the same roof with you. Best to suggest them to move out, even to the extent of renting a house. It's their problem to find a separate home.
More the distance between you and your children's families, the better is the relationship with your in-laws.
2. Treat your son's wife as his wife, not as your own daughter, maybe just treat her as a friend. Your son would always be your Junior but, if you think that his wife is of the same rank and if you ever scolded her, she would remember it for life.
In real life, only her own mother and not u will be viewed as a person qualified to scold or correct her.
3. Whatever habits or characters your son's wife has is not your problem at all, it is your son's problem. It isn't your problem as he is an adult already.
4. Even when living together, make each other's businesses clear, don't do their laundry, don't cook for them and don't babysit their children. Unless, of course, there is a special request by your son's wife and you feel that you're capable and don't expect anything in return.
Most importantly, you shouldn't worry about your son's family problems. Let them settle themselves
5. Pretend to be blind and deaf when your son and his wife are quarreling. It's normal that the young couple does not like their parents to be involved in the dispute between husband and wife.
6. Your grandchildren totally belong to your son and his wife. However they want to raise their children, it is up to them. The credit or blame would be on them.
7. Your son's wife need not necessarily respect and serve you. It is the son's duty. You should have taught your son to be a better person so that you and your son's wife relationship could be better.
8. Do more planning for your own retirement, don't rely on your children to take care of your retirement. You had already walked through most of your journey in life, there are still a lot of new things to learn through out the journey.
9. It is your own interest that you enjoy your retirement years. Better if you could utilise & enjoy everything that you had saved before you die. Don't let your wealth become worthless to you.
10. Grandchildren don't belong to your family, they're their parent's precious gift.