Thanks a lot Tom & Sander,
Issue resolved. I have changed all the reference iobj and the main iob by adding New NAV and have also changed the existing IOBJ from DIS to NAV.
For those who landed here, we can add new IOBJ to the existing MD IOBJ and none of the data targets will be inactive, you can also change the properties of the attributes and nothing will be inactive. But while changing the properties of the IOBJ for any reference MD, there is no relation with the original MD IOBJ. both are independent. Hope this helps.
Cheers
DR