bridge 2 scripts signup together

Hello, I have 2 scripts my social network script and my shopping cart script... When people register to the social network I need them automatically to be registered into the shopping carts database as well so they dont have to signup twice to access both scripts and parts of my site.... I need a very talented and very professional php/mysql expert to do this as the shopping cart is x-cart and my social network script is socialware so please no new coders I need a serious expert who can complete this task with 100% accuracy without errors because we are launching Tuesday and this has to be done this weekend so it fully works... and we have no room for delays or errors... More work will be provided as well if you provide top quality satisfactory work as we have many on going projects... I need someone who can start work immediately after being hired Also just because the maximum bid is set at 75.00 USD that doesn't mean bid the highest just because you can, keep in mind we will pick the best quality as well as best priced for the job. thank you!