I came up with 2 to the n power- 1=y
n=# of people
Y= number of relationships that need tending.
So when it was just M and me that number was a reasonable 3.
When we added Andrew is rose to a tough but doable 7.
Now with Miranda is is a whopping 15.
Sheesh! That sounds like a doozy. The math gets more complicated because some of the relationships get different weights and priorities. Some will tend to drop off entirely unless we really make an effort. Some will need more deliberate focus than others.
Here is my back of the coloring sheet math. I will not be offended if someone disproves my proof. I'm on beautiful mind amounts of sleep.