rubyrigz
You're perhaps a bit misinformed or I'm perhaps misunderstanding you. There is no 'emergency flight plan' by default in the 777 FMC.
There is one active flight plan. There is also a route 2, which can be any other plan. It can be used in a variety of ways, for example route 1 copied identically in to route 2, but at the end of route 2 have a different STAR or approach. Many also will use route 2 to input enroute diversions, around high terrain in the event of a depressurisation or engine failure, etc.
Regardless of what you put in the second route, it only takes 2 button pushes to activate it. The first push brings up route 2, and the second push 'executes' it, which makes route 2 the active route. ATC via CPDLC/ADS-C will not see anything from route 2 until it is 'executed' and actively navigating the aircraft. Likewise for any amendments to the active route 1.
Over the planned route of MH370, I don't see a reason for route 2 to be different to route 1 in the cruise phase. I also would find it highly unlikely that route 2 could be inadvertently selected AND executed. If it was, and a turn to the left suddenly ensued, why not just re-activate route 1?