cross DIT/TLD rootdn - or allow a foreign rootdn

hi everybody

I'm just looking at the surface and still have lots to read/lean, but I thought this one should be easy to achieve/set up.

Having multiple top level domains I wanted to allow rootdn from other domain (say B) to have similar access rights to rootdn of home domain (say A) and i put this into config of A domain

to * by dn="cn=manger,dc=B,dc=topdom" manage

but I get infamous:

Insufficient access (50) additional info: no write access to parent

Is possible what I try to do, does LDAP allow, i prepared for such a scenario? If yes can I get some light shed on what I got wrong or did not get at all.

many thanks.