INDEX MATCH A PARENT

I have a sheet with raw materials used to manufacture a product. Currently, I am looking up the raw material available units by using an INDEX MATCH formula to match the Inventory ID on this sheet to the Inventory ID on a sheet that shows available units.

Here's a portion of the sheet used to produce the product:

The formula in the RM Available Units column is:

=INDEX({3 Corum RM Available}, MATCH([RM Inventory ID]@row, {3 Corum RM Inv ID}, 0))

The sheet that has the availability data looks like this:

As you can see, I'm currently showing the units available of that particular batch purchased using the Inventory ID, but I want to show the availability of all batches - the PARENT. For example, in this case, I actually have available 407 units of Tamanu Oil.

What formula do I need to use in the RM Available Units column to get this information?