Here's another bit of data:
Same day, two leg DH to Europe. Deviate first leg planning to meet up with scheduled second leg in DFW.
Last minute issues require a new ticket purchase for flight from DFW. I decide to do that via VIPS. When I click on orange box in deviation and deadheading section, I see a message telling me that I'm inside the 60 hour deviation window. No problem - I just want a new ticket. So, I disregard the message warning me that I'm going to deviate since I'm inside the 60-hour deadline and I'm not allowed to deviate any additional legs. I buy the ticket but also deviate the second leg I wasn't planning to check the box for. Hmmmm. Rules are rules until they're not.
I always knew we could call crew scheduling and deviate inside 60 hours but I wasn't aware that VIPS would let us do so as well. Got to DFW and did my final check-in because I have a ticket on the scheduled DH.
Bottom line - I'm now in the scenario we've been discussing for a while in this thread but not intentionally. I'm kind of itching for a flight problem now just to see what happens. Maybe I'll call crew control and ask them what they think would happen if my flight cancelled just for grins.
P.S. FWIW, I did call them and the random 777 scheduler in crew control I reached, Paul, told me that once I performed my final check-in at the gate in DFW, I would be considered back on the trip. IF my flight had cancelled, he would be responsible for getting me to my final destination and/or dealing with any follow-on issues resulting from the disruption.