Improvements to Host-only network configuration flexibility

I use Pro edition and I use Host-only networks extensively. I would like the following enhancements as a matter of urgency please:
1. A way, via the GUI, to specify the IPv4 and IPv6 subnet for the Host-only network when it is being created and a way to change the values for an existing network.
2. A way, via the GUI, to set the IPv4 IP address and the IPv6 address for the *hoist* VNIC that gets created for the host-only network (when 'Connect the Mac to this Network' is checked). Currently an IPv4 address is auto assigned (always .2) and no Ipv6 address is assigned - I have to ad it manually using ifconfig which is a nuisance.
These seem like obvious things to be able to do (even VirtualBox supports this) and I was amazed to find that Parallels does not have this functionality :-(
Thanks, Chris