Reconnect child domain to parent AD forest without demoting child domain controllers

Hi all,

At my parent AD forest with 2 domain controllers, I cannot see both my child domain controlers in AD Sites and Services. Repadmin status is all "0" which is good but it is only replicating between both parent domain controllers. DCdiag shows KCC event errors below.

"The partition DC=child,DC=parent,DC=gov,DC=sg should be hosted at site CN=HQ,CN=Sites,CN=Configuration,DC=parent,DC=gov,DC=sg, but has not been instantiated yet. However, the KCC could not find any hosts from which to replicate this partition."

At my disconnected child domain, in AD Sites and Services, I can see both parent domain DCs and child domain DCs. DCdiag shows KCC errors below.

"The event log Directory Service on server dc.parent.gov.sg could not be queried, error 0x6ba "The RPC server is unavailable."          

"The event log Directory Service on server dc.parent.gov.sg could not be queried, error 0x5 "Access is denied."

How can I create the replication pairs in the parent domain? As the child domain controller is missing, I cannot manually create a NTDS connection. I tried running repadmin /kcc but it did not help. I have also verified that there is no lingering objects in Active Directory. Domain and trust ports between parent and child are allowed as well.

Regards,
Chiew Sheng