Hello, I am back from an absence of many years so some of my understanding may be a little off.
At the end of the age when choosing to stay with the kingdom or joining a random kingdom I would like to see another option.
Choose to join a random kingdom with select kingdom mates.
Perhaps you do not wish to stay with your current kingdom, but you want to play together with your friends or family. It would require both provinces to be in the same kingdom and both to choose each other. Each other province you wanted in the group would need to also choose you, or someone you have also chosen, who chose you.
I will be staying with my kingdom next age, but if I wanted to random on I could only do it if I was guaranteed to be in the same kingdom as my wife and son.