Flatten multilevel Bill of materials

Hello,
I have a Excel bill of material i can get out of Solidworks (3D design program).
I either have the option to do this as parts only (without the subs) or full structure (as the example).
I would like Excel to calculate every Doc Nr and quantity.
Parts and subs can be have quantities that need to be multiplied to get a complete bom.

example of what i would like to create: (column numbers in the example in brackets)

level(A) docnr(C) quantity (N)
1...........SW1...........1
1.1........SW2...........2
1.1.1.....SW3...........2
2...........SW4...........2
2.1........SW3..........4

Export should be
Docnr quantity

SW1 1
SW2 2
SW3 8
SW4 2

is this feasable? can somebody put me in the right direction?