When you and your child go to visit grandparents or other relatives, who will do the disciplining? Whose rules apply- yours or Grandma's?
Most of the time it makes sense for the house rules to apply rules of the house you're visiting. You can decide with your children that some behavior may be all right at Grandma's but not all right when they get home again. For example, grandparents may permit children to stay up latter than is allowed at home. Or allow two helpings of dessert.
This doesn't mean that grandparents should undercut parents' authority.
Some behavior is not acceptable no matter where it takes place. For example, jumping on the bed or furniture is a no-no. Period.
As parents you are the protectors of your children, even when it means your wishes go against grandparents' or other relatives' wishes. Sometimes you must insist on your own rules for your kids' sakes.