Christian
Tifanie would probably get to know Chris through work. She works at the Dept. of Mysteries, but she needs to get to know someone who can write news for that. Then if/when she finds out he's in the Order, she will definitely want to pick his brain.
Don't know if Destrey would do much with Chris, except maybe tease him. How awkward is he?
Elliot is a muggle, but if he met Chris, he'd try to get muggle ideas published in the paper. That could be fun. He'd also probably try to lighten Chris up a bit. They could hang out together.
With Hayley, Tif might encourage her to become a Death Eater specifically so she can use her to find out about Calli. What'd'ya say?
Destrey wouldn't mind having a Death Eater friend. Maybe they could hang out sometime.
Elliot doesn't know what a Death Eater is. If you want to introduce him to the concept, that would be cool.
Chocola
Both your characters were at school when Caelani was working there. Tifanie might want to befriend them just to get more information. Find out exactly how bad her sister had become.
Destrey would probably hate both your characters because they have children and she thinks that's gross. She might even try to talk Aria into getting an abortion.
Okay, so Elliot would be all about "Wizards be crazy" at your characters. He's like that about most wizards though. Also, he's a doctor (or will be), so he genuinely would try to talk Aria into having an abortion, for her own good. And he'd back up his argument with statistics. I think there's potential for hilarity there.