Azure and on premises AD have unique suffix ( card.local and Q.com)

in the current scenario. we have already office 365 with Azure ad (Q.com) and Active directory (card. local). we wanna establish the connection between two unique AD via azure connect.

what should I do?

As far as I read, if I create the same suffix on-premises AD server {

1. Open the Active Directory Domains And Trust console and select Active Directory Domains And Trusts. On the Action menu, click Properties. On the UPN Suffixes tab}

and change the suffix of all users. does it makes work or not.

how supposed we to be AD work in the local network. while joining domain what suffix we have to use.