Item consisting of multiple items

I would like to manufacture Item consisting of multiple smaller items, which also need manufacturing, is there any way to somehow do it? I have create BOM for Complex Item consisting of smaller items that also need some operations, but after creating work order there is only list of every operation for all of smaller items, but not any info about that smaller item.
The problem is, that I need to store smaller items in warehouse untill all of them are created and then complete whole complex Item and I cant find any info where and when the smaller Items are created or stored or something. Is there any chance, this functionality is implemented in ERPNext or do I need create something custome? Thx in advance.