Hi,
I tried to add new interface to hosted engine via GUI.
It got added but network was not accessible from hosted engine (ping was failing)
So I got old mail thread for adding "Multiple Nic on hosted engine"
I tired to follow but not found this file for ovirt 4.1
/etc/ovirt-hosted-engine/vm.conf
http://lists.ovirt.org/pipermail/users/2014-November/029236.html