Happy New Year. Hopefully you have had an enjoyable holiday. If you are like most people then you will have had some pleasant moments and some more difficult moments. One of the things that can help when emotions are high is co-regulation. To co-regulate means that you do something to calm both yourself and someone else down. These are some ideas for co-regulation:

Turn some music on that will change the mood. This is particularly good in the car.
A parent can push a child on a swing. The swinging will calm the child down, and the parent can calm down whilst pushing. There are also some swings built for parents and child.
Pour cold water for everyone to drink
Give the other person a hug!
Place a heavy blanket over all of the upset people. This option is better when it is cool!

There are lots of different ideas. I am sure that you will think of something that can be calming for everyone in your family.

One thing that some people are concerned about with co-regulation is that you may be "nurturing" someone when they have behaved badly. However it is important that an individual learns how to calm down and with co-regulation you are assisting them to learn that there are ways to calm down. Learning the skill of calming down will mean that the person is less likely to engage in the poor behaviour. Punishment is a much less effective strategy in assisting the person to learn new skills to cope with their emotions.