If everyone does get sick, it helps to have some basic tools in place to preserve as much sanity as possible.
I bought thermometers for every person in our family, and wrote each person's initial on one of the them with a paint marker. This way, when the whole family gets sick, we don't need to share thermometers (and our cold germs.) We can take all the kids' temperatures simultaneously.
The school-age kids can push the buttons on the digital thermometers and take their own temperatures. The thermometers save the last temperature recorded. This way, when it gets very busy, the thermometer with the person's initial has the latest temperature recorded. If I'm tending to one child, the others can leave their thermometers on the bathroom sink for me to find when I have hands free.
We keep a Tylenol/Temperature chart posted on the inside of the medicine cabinet. When a child gets sick, we weigh the child on the bathroom scale and record the child's weight on this chart. The corresponding dosage of Tylenol (or equivalent) gets written next to the weight of the child. This is a lifesaver when the whole family requires different dosages.... It's easy to mix up the dosage schedule without this.
Here is a sample of this list as we use it. (Note to family members: This file uses sample data as an illustration - everyone is healthy right now, TG, no worries!)
(free) generic version/template for this chart for you to use.
Here's a photo of the chart, taped to the inside of our medicine cabinet:
May you rarely need this list, and may whatever is causing the family of fevers pass as quickly and painlessly as possible.