(CNN)  -- In order to maintain peace at home, President-elect Barack Obama might want to have some very important talks with his wife and mother-in-law before moving into the White House.



President-elect Barack Obama's mother-in-law Marian Robinson joins him on stage on election night.



Like some 4 million other multigenerational U.S. households Barack Obama's mother-in-law, Marian Robinson, will join the Obamas at the family's private quarters at 1600 Pennsylvania Avenue.



In about 1.3 million American homes where the parents are head of the household, at least one grandparent lives with the family.



Having a grandparent living with a family can be a wonderful and beneficial addition to the family, says psychologist Elaine Ducharme, but only if everyone can navigate the boundaries.



The key issues that need to be discussed between grandparents and parents are privacy and the discipline of the children, says the psychologist, who practices in Hartford, Connecticut.



Dannee Brown agrees and says having those discussions and setting ground rules ahead of time is better than making it up as you go along because then feelings can get hurt.



Brown always knew her parents, Bill and Mary Lou Wade, would one day live with her and says she couldn't have survived without them after she and her husband separated. But disagreements over the disciplining of her two children sparked conflict.



"We've had some knock-down, drag-outs about discipline -- especially with my dad," the Fredericksburg, Virginia, woman says, "I finally had to say, 'I'm the mom -- you're not -- don't tell me how to raise my kids.' "



On the flip side, Brown's mother would like to be just a grandmother who spoils Noelle and Ethan -- instead of having to play disciplinarian while Brown is working as a nurse-anesthetist.



The Wades have a separate apartment in the lower level of Brown's home, but spend winters at their own home in Florida. That gives them all a break from each other.



Brown describes it as a "four-month time to really appreciate them" for all the cooking, cleaning and home maintenance her parents do along with the childcare.



She and the children miss the grandparents so much during this time that they usually make one trip to Florida so they can spend time with "Nanny and Pop."



The 'Aaah, go away!' effect



Along with establishing guidelines for everyone's role, Ducharme says both the parents and grandparents need to address privacy issues.



"I think privacy is key -- making sure that everybody has a place where they can have some privacy," says Ducharme.



Brown says she sometimes wishes she could have a little more privacy in the evenings now that she is working days. She gets home from work and spends the evening with her children and after they go to sleep she looks forward to some time by herself. But sometimes her mother comes upstairs to chat.



"That's when I want to say, 'Ahhh, go away!" says Brown. "I don't say that, but I'm thinking it."



And even if everyone agrees on a plan ahead of time, it would be wise to expect irritations to pop up every now and then, the therapist says.



"Trying to live together is really about problem solving," Ducharme says. She tells her clients if they all focus on finding a solution to the problem and making it a win-win for everyone involved, it takes the emotions and hurt feelings out of the equation.



Clearing the air



Ducharme suggests holding a family meeting where either party could say he or she is feeling stressed about an issue or someone lacks enough privacy.



But watch out for red flags during discussions prior to inviting your mother or mother-in-law to move in.



"If you really don't communicate well with this person, and when you try to communicate your feelings and ideas it always ends up in a battle -- then it's probably not a
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