Expanding Text/Combo Box

This will be a tricky one!

I have a bill of materials screen, where my operators will input parts that they require for a job

From this they have the ability to click on the part number they require to check if there is stock available in our stores

This will open the warehouse screen which is set as a continuous form.

The structure of the warehouse records is 1 line per batch. Each batch can contain multiple qtys.

I.e Part Number - JF5650 could show Qty: 50

When the operator goes into this screen i have given them the opportunity to reserve a some or all of the existing stock qty from a batch to a work order. They can do this by selecting the work order in a reserved combo box, and by typing a qty to reserve to the qty reserved text box.

Hopefully this is all making sense so far. Everything i have explained above works fine.

My problem is,

Many different work orders may require stock of the same part, my current setup does not allow the batch line to reserve against more than 1 work order.

Can anyone think of a way around this? At the moment i am playing on the idea of creating a seperate table for reservations linked by warehouse record which will allow the multiple lines but bringing that into a continuous form still has me thinking.

Adding multiple reservation and qty boxes is not an option. And i don't really want to change design to much as this db has 80 odd forms all doing there bit.

Thanks AOG (if i make any progress i'll keep this thread updated)