So if I understand this right, your question is, if you can connect your travel to a trip that has no deadheads?
It's perfectly legal. You don't have to have a deadhead to claim travel. For example, people based in Memphis have trips that begin and end in Memphis, with no deadhead, and as long as they stay within all the other rules (no greater than a 24 hour stopover, 48 hours international stopover), it's legal.
Now I don't know if something changed in the new contract, I didn't think it did. I also don't want to steer you wrong, so maybe someone else can weigh in. I suggest you email crew audit and tell them this is the flight you would like to take, is it legal. It kind of sounds like it's semantics as far as the "scheduled assignment". It's not as if you can only travel from/to where you start your trip, unless something major has changed. I have found crew audit to be very helpful with travel questions.