There is command 'Replace Component' in NX 8 and I hope that it will also be available in NX 7.5. But you can not replace a component with another having same name. There is no simple way to do this.
With some rework depending upon your drawing, you can make "DETAIL_A" as displayed part. Create a new drawing part with reference to the "DETAIL_A" then copy paste the drawing from "DETAIL_A_DWG" to the new drawing part in the drafting.
The "Part is Reference Only" status can only be changed in a Teamcenter managed session of NX via the "Component is Reference-Only" checkbox on the Component Properties dialog:
This is independent of the component being a "drafting component" as indicated in the Assembly Navigator as an icon with a yellow block with a drawing sheet in the background. When checked, the "Component is Reference-Only" checkbox removes that component from the BOM in Teamcenter (in newer versions adding a view of a part, (a.k.a. drafting component) also checks "Component is Reference-Only", but it can be disabled afterwards).
What is it that you're trying to do that you believe "Part is Reference-Only" is affecting you?
In Native NX you would have to set the attributes:
to have it be ignored in the BOM, aka Parts List
Could be the attribute REFERENCE_COMPONENT is set? ref IR 7798551
Its not effecting anything in our side, but our client want the drawings to be with out reference parts in the drawing. I tried coping, exporting,replacing, nothing was sucessful.
In this case the part is added later on the drawing and not in an good way wat you normall do when working in Master model Drawings.
So this part is just added in the drawing as reference.