I'm gonna have to side with Silverlight. Characters shouldn't have relationships unless the two players in regards to it agree. It'd be like me saying My character is the ancestor of Sanae Miyasu without discussing it with NieRDackel first. Yes, I and many other people don't, and shouldn't - have a problem with sharing names. If Silverlight had made a character called "Suguha Hanamura" or what not, I wouldn't have issue with it. What I would have issue with would be him associating with my character in terms of family without my prior approval and discussing it in detail.
Furthermore, dragging people into a chat without even informing them of what they're being dragged into is not suitable for mediation. Things like what Silverlight said (being with Shiz in a FL Chat, especially) are a good reason why.
Edit: It seems there's more to this than I assumed was visible, I'll refrain from continuing, but my point still stands, regardless, to a general extent.