Ability to Split Items in the Cart Based on Different Fulfillment Options

Currently on the product listing page a users sees availability by fulfillment option (i.e. ship to store or ship to me). If they add an item to their cart they cannot change the fulfillment method in the cart itself. If they want to change an item from 'ship to me' to 'pick up in store' they have to dump the cart and start over again. Give the user more flexibility in this regard.