This is a question directed at developers and people who have already played the game.
When you send a fosterling to another Lord or a foriegn court, do you get a cassus belli if that fosterling is killed (by unatural causes) whilst under their protection or is it just a significant relation hit?
I know there is a potential that that might be exploited as a way of getting easy causes for war but surely it would make sense as you have entrusted your family member's life in the hands of another character. The reason you would send a child away would be to show your trust and favour. If that trust is broken, I think the penalties should be severe.