Recursive API call to explode BOM

The internal reporting tool in Aras doesn't work for us therefore we have to use external tools. 

I need to explode the BOM downwards for parts. Use this data in PowerBi to create reports. 

I have figured how get the BOM structure but it only gives level 1. How do I drill down? 

This is my call to get level 1 BOM

url/Part('9A75B30B66A5465BA372C30384133345') BOM($select=quantity,nmg_material_record;$expand=related_id($select=item_number,unit,major_rev))