Whoa, this sounds complicated.... and why are you still using SME 6.x?
SME Server was never designed to do what you are trying to achieve here, so I don't think anybody is going to be able to offer much advice (prove me wrong folks!). What I would suggest is, if you are keen, try installing a copy of SME 6 in a virtual machine (VMware Server maybe) and then trial your plan and iron out any kinks in it.