You can define multiple lists. If you are not logged in your lists are temporary but will be saved when you login.
Loading your lists...
Different indicators are shown if a product is in the current list, another list, or none of your buying lists.
You can build up lists for different projects. You can save carts as lists, and add lists to carts.
If you would like to create merged or modified lists just add them to an empty cart, amend as you like and then save the final cart as a new list.