Sales BOM in Scheduling Agreement

Dear Experts,

I have an explode BOM at Scheduling agreement level, and for this I am use LUMF (TAP) for main item and Z*** for sub item.

But standard system suggest LPN item category for schedule line, but for BOM I used TAP and Z***.(Copy of LPN)

Now the problem is when I double click on the item and wants to assign schedule lines, system shows the line are in (Gray) page.

System performs in the right way, but as per my scenario I want to explode BOM and to have maximum schedule lines at every item.

Can any one have any suggestion in this. If require any further clarification please do write

Thanks and regards,