Remove a parent BOM using ECO

Hi,

When I try to expire a parent BOM using effectivity dates ( 31 march 2020)

I tried using R: remove P: parent and C Change parent.

after trying to populate I get an error:

In case of R

Error Detected: Existing Bill Ineffective on Date Req'd

In case of C:

Error Detected: Related Items Missing From Item #200851.

Related items field does not get poplated but in P30131 the parent is there?

I have two questions:

1. Can this be done with ECO to make a parent BOM ineffective?

2. If it can be done then is there a document explaining how to do it?