Confusing Query-type Help

This is a bit confusing, so I'll try to explain it well.

Two tables. One has a list of metals. The other has a list of submetals, and what basic type of metal it is. It's grabbing the second column from the first table. Makes sense, right?

Now, I have another table, with links to both of those fields. What I want it to do is when it picks the metal type, to filter the subgroup to only the types it has associated with it to the basic metal type. Not sure if that makes sense. I'll supply an example.

Table 1
Aluminum
Brass
Copper

Table 2
Subgroup Basic group
License Plate Aluminum
Iron Aluminum Aluminum
Yellow Brass Brass
Copper Wire Copper

Now, if in Table 3, they choose Aluminum from the drop down box for basic metal, I want the dropdown box for the subgroup to have only License plate, and Iron Aluminum. For Brass, only Yellow Brass, and the same for copper.

Any ideas on how to implement this?