Assembly BOM is pulling parts from a different assembly

[grant.klosterman]

Hello Experts,

I am trying to create a BOM on an assembly drawing. I have gone through much trial and error to get to a decent place. However the single part numbers seem to be giving me a headache. Is there a way to filter by assembly so that parts in different assemblies can have the same single part number? I wish to use the same custom connections between different assemblies and keep them linked so that if something changes, I would only have to change it once. For example, the channel mounts pictured are also used on assembly 17. Therefore, on that assembly sheet, I would want the channels to be named 17b. 

I notice the issue for assembly 12, part b is supposed to be the connection plate. However the BOM displays the base plate from the connected column assembly (11), which is also that assembly's 'part b' (I would like it to be named 11b). However that same base plate is used on another assembly (16), so I would want that base plate named '16b'.

Any assistance to help me understand how the BOM filters it's parts and advice on how to get where I need would be much appreciated. 

Thanks

  

[basilWQYNL]

could you also provide the numbering method you are using now