Well We have an 11 year old, a 15 Yr old and shockingly after thinking we were over the hill, currently it appears number 3 is developing after 8 years of trying-boom one month of medication changes and B12 injections.
(both absolutely amazing and slightly terrifying at our age in our 40’s)
My suggestions are keep to a routine and make time for yourself as parents and accept help from close trustworthy family members.
Be kind to your partner and yourself as sleep deprived, take a deep breath if your feeling stressed and avoid conflict due to the sleep deprivation.
Sometimes a parent sitter is what we had, we went to bed and had grandparents in same house watching baby or an hour on a date at local cafe or similar 10 minutes down the road-but keeping relationship and communication etc going.
We have a weekly family meeting, there is an item to hold and the person talks in turn-we have a planner and chores.