Luggage!!!

Hello Everyone,
I am flying to Los Angeles on Monday (Upper Class) and I was initially going to take 1 suitcase however I have now admitted to myself that I need an extra suitcase with all the shopping I plan to do in LA.
I don't see the point in buying an extra suitcase in LA when I have suitcases in London so I was wondering, will Virgin let me check in an empty suitcase? Or do I put the half packed one into the empty one? I know I have an allowance of three suitcases but I just wondering if anyone has done this before? Has any information?
Any help will be appreciated.
I am flying to Los Angeles on Monday (Upper Class) and I was initially going to take 1 suitcase however I have now admitted to myself that I need an extra suitcase with all the shopping I plan to do in LA.

Any help will be appreciated.