I think the All-Girl alliance will be upset at first...but remember...this gives them one more person in the alliance.
However...I think the chances of Adria or Natalie winning are slim because the other HG's will feel that they don't deserve to win because of the swapping.
Another thought...go to the official CBS website and look at the thumbnails of the pix of the houseguests.
http://www.cbs.com/primetime/bigbrother5/index.shtml
There are three blank squares. We know that Natalie will fill one of those squares once she enters the house full-time. Who will fill the other two squares? Are there other twins swapping as well?
NOTE: When you go to the CBS website, please know that it will only be as current as the episodes aired. For example...it shows that Jase is nominated for eviction. However, those who have watched the live feeds know that he won POV and took himself off the block. Marvin replaced him, but the CBS site doesn't show that yet.