our miko can be aggressive at times as well, especially with our cat.
if you can, continue to be patient and do lots of research. you might be able to make her a happy member of your family.
if she bites at your other dogs, you may want to try giving her a time-out in a completely separate area (we use the bathroom). leave her in there for half a minute to a minute and don't open the door or talk to her (or yell at her) until she's quiet. you can also try calling her name when she's being bad (with enthusiasm) and if she comes to you, then you can click-treat (research clicker training)
if she's chewing on something she shouldn't be, then in order to make you taking that thing away a good thing, you'll have to replace it with something better, like a treat. get her to come to you and get her interested in what you have to trade. if you shout at her, it elevates her aggression so try to avoid doing that.
as for her wrecking the furniture, i wonder if she would do better with crate training when you're gone or trying to take a nap. also keep in mind that at 6 months old, she's teething and so will be very chewy. when she's in the crate, even if she barks and whines, she'll get used to it and realize that you aren't responding and eventually should stop. if she's destructive while in the crate, then you might be dealing with separation anxiety. there's plenty of info online regarding how to deal with that.
it's possible you may need a behavior modification trainer to come to your home to see the problems as they're occuring and help you to curb them.
i hope you're able to get things straightened out. hang in there!
