[derisgun]

My parents own a E. Bull terrier that had a rough start and has never been mentally stable.
She was taken from her mom at a week old and taken to the states where she was placed in a foster home with a nursing mom so she wouldnt loose out on social skills.

She has always been aggressive with strangers, she has gone after my dad a couple times when he walked into their room at night and now in the course of 2 months she has gone after my 12 yr old sister.She already has bit my sisters friend when she was about a year old (shes 3 now) and caused a huge bruise and possibly broke skin I dont remember. She has also bit my mother a few times pretty bad because she gets worked up some times its over something like play fighting other times it's over someone just moping. She now is growling at my mom over bones and lunging in her crate if she has any bones (which if that was the only problem I would say its a pretty easy fix).

She has horrible OCD which isn't un common in BT's but the aggressiveness IMO shouldnt be tolerated and I know a lot of people also agree.
One day she could easily grab my sister and she is not the type to just bite once she keeps going.

I briefly talked about it with my mom but I dont think she took it too seriously.
Does anyone have any ideas of how to nicely try and tell someone their beloved dog should be put down? I dont want to go about it the wrong way and cause conflict.