Maintain the link node in a hierarchy

Hello,

I have loaded 2 hierarchies H1 and H2 from ERP system and maintained a hierarchy Z in BW consists of H1 and H2. The node names are exactly the same of the 2 loaded hierarchies. Now I want to maintain the “link node flag” for the 2 nodes H1, H2.

When I maintain the hierarchy this field is only displayed (and it is blank).

How can I change this field to ‘X’.

Thanks!