DOOJOON

Since doojoon does have an older sister he wouldn't do make simply because she's older but his sister does have child so he would be repulsed.

"I'm sure you're having a great conversation but she's happily married and has a wonderful child so leave."

HYUNSEUNG

If it was his actual younger sister he would be so overprotective he'd see guys flirting with her and would get annoyed right away he'd walk over glaring at the boys flirting with her.

"Do you know them?"

He'd ask his sister but his eye's never left the boys

"No i just met them."

She'd respond quality.

"Alright leave you damn rascals my sister is off limits to you..and every other guy out there."

Hyunseung would watch with smirk as they walked away.

"Oppa!"

She'd whine

"No you're to young don't even think about it."

JUNHYUNG

His reaction would be like hyunseung's he'd even go as far as to hold his sisters hand.

YOSEOB

I think if it was his older sister he would be weirded out because to him she's his flash and blood and he doesn't see her in that light so to see someone looking at her in that light would make him uncomfortable.

KIKWANG

Out of all the members i think kikwang would be the only one who wouldn't really care like it's his sister life and if she seems interested who is He to get in the way of possible happiness for her? But if she was uncomfortable and the guy was being very Persistent he'd step in with no hesitation.

DONGWOON

His reaction would be like yoseob's he'd be uncomfortable because ew why would someone flirt with my sister!?! but like kikwang he would step in if the guy was making her uncomfortable