It will be interesting to see if any of Kat's family are there. I remember when Kat's brother died, she took Nate to his funeral & to meet her family (that all happened off screen). Nate was going to break up with her beforehand, but when she asked him to go to the funeral with her, he didn't break it off till they came back to SB. She was angry that he let her introduce him to her 'whole family', while knowing all the time that he was about to dump her. So, will any of her 'whole family' come to the funeral? I hope so, at least her parents - we will see. The other thing, of course, is that the Chapmans have now lost both the brother & sister (Kat). I would have thought they might want her to be buried close to them/with her brother, rather than way off in SB??
As for Patrick, I think it would be highly unlikely he would return just for the funeral, but you never know. It would be up to the availability of the actor of course (Luke McKenzie), but I doubt they would bring him back just for that (& if they did, I think he probably would have been in some of the photos we have now seen of the funeral). If he doesn't return, I hope they at least mention him/say why he can't come etc.