That is the thing with multi-level BOM. Components might be done also by few other materials thats why it is called as parent in BOM. Thats the trick of extract i have. On the other hand in Output you have Parent-parent item that is made of few components, and those components might be done by another components. So there is fully finished item that is made of Comp 1,2,3,4 and Comp 4 is made of Comp 9 and Comp 10. Comp 10 can be made of Comp 11,Comp 12 etc. Thats why in output there is Item 1 in B column.

Does it make sense?

Thanks in advance!