Perhaps you are going to be stuck with the Brother-in-law who keeps himself to himself & does not offer much in the way of conversation - In this case - Have some Grapefruit Essential oil on the go - Commonly known as the "happy" oil it get's people chatting - It is also great for the immune system so can help you to ward off all those Christmas bugs people may share with you & aids detoxification.
Do you have the Mother-In-law from Hell who will criticise everything you do? In this case - Grapefruit may also come in handy - or other uplifting oils such as Frankincense, Geranium - or my personal favourite - Neroli! - These oils will perk up the mood of anyone who is not feeling the festive spirit!
For yourself - to help deal with all the stress and strains of dealing with individual characters, wrapping presents, food shopping & cooking Christmas dinner - Opt for a blend of Bergamot, Lavender & Sandalwood.
For emergencies such as waking up on Christmas day and realising you forgot to buy the Turkey - use a blend of Lavender & Chamomile - (Then call a friend or relative and invite yourself round and pass on all the tips above!)
Individual cautions apply - please ask your therapist for details.