DirSync from separated AD domains to one tenant

Hi!!

We are in the process of planning a new Office 365 migration and the customer wants an Active Directory synchronization with passwords included, do not wants ADFS, only DirSync with passwords.


They have 3 Active Directory domains in separate forests. It is possible to install the DirSync tool on each domain to make a sync to one Office 365 tenant? 

Thanks

Juancho