crusader-kings-2
I have my daughter married my liege. They have a daughter (my granddaughter).
I also have a grandson (from a son, who died).
To become a liege (in the next generation) I want to marry them. But when I offer the liege to arrange a betrothal I can't select my grandson. He is not landed, is 8 year old.
I guess I realized the answer: I can only arrange anything (either marriage or betrothal) for somebody who is in my court.. Am I right?
On your first question: disinheriting your heir is not possible unless you have elective succession. Then you change for example choose to elect your second or third son. Most of the time your vassals will elect the person you elect. Off course there is a chance they will elect someone else, so it's tricky.
On your second question: yes, it is possible. I have done it before (horrible me) when I was in kinda the same situation as you. My heir died relatively young and so his only son became my heir, but had really bad traits. So I plotted against my grandchild (who was about 4 years old) and managed to successfully kill him. There is a catch however, which happened to me. The plot was successful but the truth came out that I did it, so I got the Dishonorable trait and, even worse, the Kinslayer trait which gave me massive relationship penalty to my family and vassals. So yes, it's definitely possible but there are some serious risks.
If you want to find out the size of a single realm, I would go the way bd33 suggested.
But if you want to get an overview of the sizes of all realms, go to ledger:
Then get to its tenth page (“Independent States”) and click on the “Realm Size” column heading to sort the list by that:
Best Answer
You are correct. You can only propose marriages/betrothals when one party is a member of your court (or yourself).
There is, however, an exception to this. You can choose to control who your children marry if they become landed and leave your court (I'm assuming you landed your son and the grandchild inherited from him). I don't know if this applies to dynastic grandchildren but there should be an option on his character view.
It's worth clarifying that the incest involved is not an issue. First cousins can marry in CK2 just fine, although you may end up with funny looking children, especially if you make a habit of marrying cousins.