Trouble creating composite table relationships from master tables in a form

[clawlan]

I may be going about this in the wrong way but let me lay it out there. I am thinking this is a pretty straightforward task but i just can't figure it out. I am also relatively new to Access. Here it is:

The purpose of my DB is essentially simple inventory control and ordering of safety equipment (goggles, gloves, etc). A user selects and item, then the size, then submits. All the safety items are stored in their own master table and all the possible size options (regardless of safety item they may or may not be associated with) are stored in another master table. Then I am using a composite table to create the relationship between the item and the size (each item/size relationship has its own record). I did this to maintain the referential integrity.

On the ordering form, the item combo-box is pulled from the item master table, and the size combo-box looks at the item selection, then queries the composite table for all the possible sizes for that item. Make sense? It works great.

The road block i have hit is creating a simple form that the Users can use to add new safety items and their associated sizes. Essentially, the steps would be add safety item to safety item master table, add size options (if they don't already exist) to size master table, then create the relationships in the composite table. But this is too complicated for the users and i know it can be simpler.

Ideally, the users would open the Master table form, and see a datasheet view of all the items. Then when they click on an item, it would show another datasheet view of the available sizes on that item. An to enter a new item, they just type in the new item at the bottom of the datasheet, and then the size datasheet would be empty (since its a new item), and they could start adding sizes from the size master table, or just enter in new sizes if they don't already exist. Ideas Here are some pictures:

[clawlan]

seriously? no one has an idea here?