Magento Multiple Address Module

Magento 1.4.1.1 has 2 shopping carts, "one page checkout" and "ship to multiple addresses checkout". We desperately need either: * to modify our current SAGEPAY and PAYPAL STANDARD modules to work in the multiple addresses checkout aswell as onepage (which already works). or; * The ability to record an address per product in the onepage checkout, and calculate postage per address.