Hello,
at beginning of 2017 I configured OVN in my oVirt 4.1.0 setup, with the previosulsy described notes, I think the ones here:
http://www.ovirt.org/blog/2016/11/ovirt-provider-ovn/
At that time OVN was not directly integrated in oVirt setup.
Then I applied the updates in minor releases and coming at 4.1.9 level in late January this year.

Now I plan to update to 4.2.3. I have doubts related to OVN setup.
Will the new 4.2.3 OVN setup conflict with my current 4.1.x setup?
WHat do I have to answer in setup related questions and prompt? 

In fact now, after enabling 4.2 repo and updating the setup itself, during the procedure (that I Canceled right now) I receive these questions:

# engine-setup
. . .
[ INFO  ] Stage: Environment packages setup
[ INFO  ] Stage: Programs detection
[ INFO  ] Stage: Environment setup
[ INFO  ] Stage: Environment customization

          --== PRODUCT OPTIONS ==--
         
          Configure ovirt-provider-ovn (Yes, No) [Yes]: 
         
. . .

          --== OVIRT ENGINE CONFIGURATION ==--
         
          Perform full vacuum on the engine database engine@localhost?
          This operation may take a while depending on this setup health and the
          configuration of the db vacuum process.
          See https://www.postgresql.org/docs/9.0/static/sql-vacuum.html
          (Yes, No) [No]: Yes
          oVirt OVN provider user[admin@internal]: what_to_put_here
          oVirt OVN provider password: 

. . .

          --== CONFIGURATION PREVIEW ==--
         
          Default SAN wipe after delete           : False
          Firewall manager                        : firewalld
          Update Firewall                         : True
. . .
          Set up ovirt-provider-ovn               : True
. . .
          Configure VMConsole Proxy               : True
         
          Please confirm installation settings (OK, Cancel) [OK]: Cancel

Thanks for any hint.

Gianluca