We have one...husband and I both. We also have a power of attorney for my inlaws bc they have kept my kiddos every summer since they were 2. We gave them authority for healthcare and taking care of them in case we can't be reached. It has allowed them to take kids to ER without us being there. We had a small binder for my inlaws with doctors, insurance cards, friends names that we are close too and all of the neighbors. We live in a tight knit community/neighborhood. We are friends and talk regularly with them. Hubby and I went to Paris several years ago no kids and we did an Alaskan cruise, no kids so we needed to have all the ducks in a line in case something happens.
My kids are 11 and 17 so they have all the info on their phones now so they aren't as much work as they used to be.