Here are some general guidelines concerning conflicts with grandparents that should be helpful.
When children who are 2 to 5 do not see their grandparents often, they often hang back, withhold hugs and kisses, and treat grandparents as strangers, causing hurt feelings and conflicts. Giving presents immediately on arrival is not a good way for grandparents to resolve this problem; it takes the focus away from family relationships and places it on gifts. It is best to warn grandparents ahead of time that this behavior is common, and ask them to be patient, waiting for children to make the first moves. Better yet, help children know that absent grandparents are "family" throughout the year with calls, letters, tapes, and photos.
Many conflicts with grandparents during the early and school years involve decisions about the who and when of visits. this gets especially complicated when a divorce adds custody/visitation rules, or when a second marriage adds more family members to be visited during holidays. It is usually impossible celebrate with every grandparent on the actual holiday, and is also difficult to divide everyone with "equal time". Grandparents need to come to terms with these realities, be flexible, understand that the child's parents have the ultimate responsibility for these decisions, and make the best of it. An ongoing positive relationship, not a particular holiday, is what really counts.
As children grow to be teens, conflicts arise between parents and grandparents about money, attire, dating, curfews, etc. Grandparents are sometimes accused of interfering. Actually, all they really need is to feel that they still have some role to play...that they still feel they are part of the family structure. Parents need to listen and appreciate the advice and support of grandparents, but gently remind their elders that they, as parents, are legally and morally responsible for guidance and final decisions regarding their children..
All conflicts with grandparents are lessened when they feel appreciated and when they see that, even though your values and theirs are different, you do try to pass on to the children some of the values and attitudes they taught you. Focus on things your children and the grandparents have in common, not on how they differ. Point out continuing family traditions and interests. Help them see how important it is for them be listeners to teens that might rather talk to them the to you, the parents. Show ways they are needed.
During the holidays, reduce stress by giving up expectations that everything will be perfect. The food, the house, logistics and gifts are not as important as your relationships and being together, no matter what the circumstances.
Suggested reading: "Grandparenting; Understanding Today's Children", David Elkind. (Scott, Foresman 12.95).