Can this type of "add to cart" be done with E-cart - see example

Hello,
i need to develop a shopping system that would function like this example:
0?N=377%20710%201626&Ne=0&Ntt=Switches&Ntx=mode%20matchallpartial&page=CategoryDisplayLevel1&isLTokenURL=true&storeNum=5002&subdeptNum=9&classNum=294

where 1 product may have multiple associated products like a cleaning product, comes in 32oz, 1 gallon, 5 gallons, 10 gallons all different prices but the same product. you'll see if you view the link above how this website has the same idea set-up where it lists the associated products with a quantity box next to each and 1 add to cart button at the bottom.

does anyone have any idea how this could be accomplished, as well as how would one go about the set-up of the DB / inserting new product in an admin... would it be insert the main product and then the associated ones in as separate line items in another table related to this main product?... this is a little different then anything ive done before so i'm trying now to visualize how this whole would be set-up.

thanks