This is actually the first time I write in this forum and this topic is the reason why I am now registered. Your story tugged at my heart so much and I've been through something like that years before...it's like emotions run wild...one day is sunshine and the other rain (or thunderstorm)...
I am glad you've found a solution to it and I know that this is just the right decision...
Our relation to our furry friends is not so very different to our friendships with other humans...some are meant for a reason, some for a season and some for a lifetime...sometimes things just don't work out as we want them to be...THAT'S LIFE!

But I think we all learned from your situation that cats are indeed as individual as each living being...some are meant to stay with us and our families and some just never fit in right...we have to accept their choices as well and here your cats have made the final choice and I'm really glad you've listened to them!

And now go on and enjoy life with beautiful Miley and her little sister Juni Rose! Please!!!