Vista - Metric Bug in Vista for multiple DSL connections

I have a rather peculiar and rare issue with Windows Vista networking. I use
cFos (http://www.cfos.de/) to connect to the internet. cFos is a virtual COM
port emulator for DSL connections and ISDN adapters, so that virtual dial-up
connections which use emulated ISDN/DSL modems/PPPoE can be used to connect
to the internet. If COM ports 1-10 are emulated, then up to 10 simultaneous
connections can be connected. Here is where my problem lies. In Windows XP,
when I joined 1 connection, it assigned a certain metric to it. When I joined
another dial-up connection, it raised the metric of the earlier connection by
1, and assigned the lowest metric to the new connection, so that it becomes
the default route. The important thing was XP could continue to transfer data
using the earlier connection, e.g. if I was downloading a file using 1
connection, then I joined another, XP continued to use the first connection
to download the file, so that the second one could be used from different
data transfer. Now in Windows Vista, I can join multiple connections, however
as soon as I join the newer one, Vista assigns a very very high metric value
to the older one, (as high as 4500 or still higher), as a result of which,
all data transfer on the older connection stops or times out. Whenever I
disconnect the newly made connnection, it resumes transfer on the older one.
The end result is that I can only use 1 connection at a time in Vista, which
is horribly limiting, vs more than 1 in XP and 2000. I tried unchecking the
automatic metric setting, however Vista seems to ignore that setting and
still assigns a high value metric to the earlier connection due to which it
stops all data transfer. Any solution to this? I am sure this is an
overlooked bug in Windows Vista.