A question

I have searched for about an hour now and have not found anything on it. Im curious if anyone knows what the chat option with rulers (so far only seen if for kings/queens) where you ask them if you can be affiliated with their line?

I Have tried it several times and all they do is say that they dont have an opinion from their family and to ask again in a week, even when i do they just say the same thing again.

First you need to obtain a really high relationship with at least one Lord in the family, and it's best to have a decent relationship with all the lords in that family.

Until you have a really good relationship (around 25-30) with the lord you're speaking with, they'll just keep putting you off.

Once you are affiliated with a family, if any member of the family is captured during a conflict, your standing with everyone in the family will drop slightly...but you'll also gain relationship every so often with them.  Other diplomatic options with any member of the family is also easier to accomplish, and if you're their king and call for your vassals to gather for campaign, they'll usually show up even if your relationship with any of them has dropped into the low negatives.

Ah thanks for letting me know, had only tried it with kings who had no families.