Install other Exchange 2010 System to child domain

Hi all,

In current HQ Active Directory, it already have Exchange 2010 System installed. Company will create other sub company and will plan to install a new Child domain (AD) and will install other New Exchange 2010 System to this Child Domain.

After I create a child domain, all existing schema already in Child domain. I want to ask that do i need to run Exchange Setup /preparedomain:child.DC.com in child domain environment again for install Exchange System?

If run of this setup command, will affect HQ Exchange system ?

If I wrong, any step I need to do?

thanks