How to add item parts/constituents/box?

Hello community can you please help with following questions.

  1. How do I add an item which has 4 parts/boxes and when that item is orders from ERPNext frontend website that all 4 parts are subtracted from stock because we maintain separate stock for all parts/boxes e.g. A bed that has 4 boxes/parts. We cant use bundle products because this item has two colours and two sizes and on frontend there is no option to show product bundle with product variation options (colour and size drop downs) Also BOM seems an overkill as we don’t manufacture these items ourself.

  2. How do I add an item that has two two colour and two size options such that in the frontend website customer can choose colour and size before placing the order

Many thanks