What is the most productive way for me to use my nieces? I have them in my court. They can get a regular marriage with rulers, but I don't personally get an alliance from any marriage they make.
Is there any benefit from marrying them off in regular marriages? (I guess their closer relatives would get alliances from these marriages, but I'm not aware of any other benefits. The children are essentially dead to the dynasty, right?)
The nieces aren't important enough to get a matrilineal marriage with anyone outside my court.
I can bribe claimants and invite them to court, then do a forced matrilineal marriage. The offspring would then have the claim (assuming it was an inheritable one) and would be of my dynasty. In the unlikely event that I need this claim, I could then give the child some land and press the claim.
But it is very time consuming to hunt down invitable claimants and it clogs the court with wrong culture males. I only really want to give them land if I'm going to be pressing their claim. Maybe a barony, but I don't have many of those to spare. There also aren't that many useful claims in the area I'm playing in, since most of my neighbors are pagans/muslims. I don't really need to spend 30 minutes looking for eligible claimants, only to get a claim that is so far away as to be nearly useless.
So what's the most productive to use my nieces? I've been spending way too much time micromanaging them and not getting a lot of benefits. And there are a lot of them to deal with.