Add more than one MailboxDatabaseCopy

Hi,

We have Windows 2012 with Exchange 2013, working fine.

DAG has two MBX in HO and DR one MBX.

Need to add DB copy in DR server. 

I can only use one DB at a time to DR MBX.

i.e, Add-MailboxDatabaseCopy -Identity DB1 -MailboxServer DRMBX.

How can i add more than one Database Copy simultaneously?

Thanks

Alagar