The Rescue of Olivia and Claire

Episode "Cheer go tell your sisters they need to get out of their room" said mom. I went upstairs to tell them but when I got to their room it was destroyed and they were not there. It was messyer than Tom and Ryan's room and thats saying something. I ran to phineas and ferb's house and told them then POOF for a few minutes it was black but when it wasn't black phineas and ferb were gone. Even their back yard was in ruins all I found was this note. It said "I have escaped from jail and I am living in danville. I have taken your friends so I can make them vanish Emma". Well that got me confused because 1. why would she do this and 2 why on earth would she take my sisters they the oppisite of friends!!!!