everbright wrote: I now have to host a VM in different LN segment, as follows, using ficticious IPs to illustrate the point:-
Host Machine: 128.0.12.100
Most VMs: 128.0.12.x
Problem VM: 128.0.11.101
What's "ficticious IPs", there is no such thing! 
Also the IP Addresses you've erroneously presented as "ficticious IPs" are actually Public IP Address that are actually assigned to someone as shown in the attached image! (The 128.0.11.0 Subnet is assigned to the same in the image.)
That said and since in all likelihood your system is behind a Router and is probably using a Private IP Address then in that case there is absolutely on good reason not to use the actual information and describe the relationship of the Topology of the LAN and the Host System and whether or not the Host is physically multihomed and active (two or more active physical NICs) and how your system is configured to access the two different Subnets. If the Host is physically multihomed and each NIC is assigned the separate IP Address then you can use the Virtual Network Editor to manually assign the second IP Address to either VMnet0 or add an additional VMnet to bind to that NIC and then configure the Guest's Network Adapter to use the target VMnet.