"A very limited amount of advice should be offered – if you can wait for an invitation all the better and don't turn it into a lecture," suggests Hale.
"Be positive about what you can and how your kids are raising their children. It's a good idea to be curious – things are done differently in every generation, so allow your children to teach you something."
And if you're heading away to visit adult children living abroad, or going on holiday together, you'll be spending even more time in each other's pockets. The natural instinct may be to take over as the leader in the family group, but it's important to support your adult children in what they are doing as parents.
"Definitely don't try to get grandchildren to side with any parent or grandparent," says Hale. "It gives children a wonderful feeling of safety if they realise the big people are working together."
Rather than being the type of grandparent to sneak sugar and salt into your grandchildren's diet when their parents, who don't approve of salty or sugary snacks, aren't looking, instead check in with the "family rules" of the home so you can support your adult children in how they want to parent.
Spending time doing something together, rather than sitting around the house — or hotel room — will also give you something to talk about other than parenting advice. For example, get into the outdoors and visit a zoo, or go for a hike — anything that gets you all active to get positive endorphins flowing.
Finding common interests, such as enjoying live music or snow sports will give you a closer bond on holiday. And remember to spend time alone with each person in the group — whether it's taking your son-in-law out for coffee one morning, or spending some time with your daughter at a day-spa — family holidays are about making connections, not just tuning out.
Trying to book an all-inclusive holiday package will also save some of the financial stress and uncertainty of who is paying for the meals and activities.
If you do sense tension or arguments, suggest going out to do something you each love to do, on your own, and re-grouping at dinner to share stories. For example, you might love museums, while your children love mountain-biking. If you've both had a great day doing things you like, you'll be more likely to have positive talk when you get back together.
Another nice idea is to bring a bit of nostalgia into the trip, as long as it's not at the expense of others in the family. An example is re-visiting a place you and your children explored when they were younger and reminiscing about the experience. Partners and grandchildren may like to explore with you, or give them the option to do something else — it can be nice for them to discover more about a person's childhood, or it may make them feel left out.
Grandparents may have more time to plan how to run the holiday smoothly, but it's not all about them making the effort to fit in with their adult children. Adult children can also do things to support grandparents to be part of their families.
"Encourage grandparents to carve out their speciality and have that as their thing," says Hale. "It might be the teaching of knitting, the cooking, the bike rides, the remote control cars, the special holiday retreats. Also, don't buy too much stuff for your kids — leave room for grandparents to shine!"
She also suggests maintaining a respectful attitude to your parents, because children will pick up on any distain or disapproval. It's not always easy to forget past hurts from childhoods, but try to talk about relationship issues away from listening grandchildren.
"Find ways to stay in touch — whether it is by phone, skype, text or old-fashioned letter writing. It means a lot to grandparents," says Jenny. "And be appreciative of the help you get. It is easy to take child minding for granted but your thanks and even help with finances if an outing is expensive goes a long way."
The happiest cultures seem the ones where extended family weave their lives together, so working on these relationships, which Hale says are the most important thing in life, can have a benefit to all involved.
"This connection of children, parents and grandparents can be an amazing gift," says Jenny.
"Being respectful, kind and thoughtful will be amazing attitudes to hold as you navigate this opportunity together."
