Flexible Multi-Machine Blueprint creation

Hello,

I am a newbie with vCAC. I know vCD and I would like to transpose what I set up in vCD to vCAC.

I wish to create a blueprint that allow users to build their own environment picking up one or several OS blueprint using linked clone deployment and allowing to use either NAT, private or external network.

I though the multi-machine blueprint type would answer exactly to my need but after creating it, I realized that you have to select at least one OS blueprint of each type.

So let's say I create a multi-machine blueprint composed of a Windows 2008, a Windows 2012, a WIndows 7, a Windows 8, a Linux CentOS, Linux RedHat, etc but my user just need one Windows 2012 and one Windows 8, he has no other choice selecting at least one instance of each.

First question : Is there a trick or something to allow users selecting 0 for some of the OS blueprints?

If not, what other deployment method I have to achieve this goal? In short, offering the provisioning choices I had in vCD.

Thanks for your help.

Sylvain