score:6
It's a little unclear, but as I understand it, you're proposing (the cities are made-up examples):
With such a plan, the remainder of your ticket will be cancelled once you miss the Paris-Moscow flight. While it's conceivable that you could slip through the cracks between different airlines' IT systems, your reservation is linked together on one ticket, and I don't believe it's likely that you'd get away with anything.
Other issues:
Also, many, but not all certainly, airlines will charge the same number of miles for any roundtrip flight between the US and Europe, making this scheme pointless. We don't know the rules of your program though.