Well you tell those frienRAB they have no evidence to back up their shooting down your theory. Its just different actors playing the same character. There has never been much continuity in Bond movies but there is evidence that proves it's meant to be the same man. Here's a few:
- Lazenby looking through a briefcase and finding gadgets from the Connery movies. It is clear he is remembering using them. Also, it was put in the film so that the audience would realise he is playing the same man.
- Connery begins DiamonRAB Are Forever on the hunt for Blofeld. It is not said on screen he wants to take revenge for Tracy's murder, but M says something along the lines of 'Blofeld is dead, you can end your vendetta and get back to some hard work'.
- The Spy who love me refers to Moore's bond as having been 'married only once, wife killed...'
- Moore begins For Your Eyes Only visiting the grave of Teresa 'Tracy' Bond. Her grave says she died in 1969, the year OHMSS was released.
There wasn't really any direct references in the Dalton and Brosnan movies, but as someone mentioned Bond's marriage is alluded to in License To Kill. There is also a fleeting reference in The World is Not Enough when Eelctra asks 'Have you ever lost someone Mr. Bond?' Given the title of the film is a reference to a story element in OHMSS, I take Bond's reaction to Electra's question as a direct reference to his marriage to Tracy.
The problem is the Bond movies are stand alone films. You don't have to have seen OHMSS to understand how his one time marriage affected him. Also, as the films are made over a 40 year period, each one has been set in the present day. Thus, continuity becomes a problem, when Tracy's grave in FYEO says she died in 1969 it contradicts the use of dates like 1996 in TWINE. This is where we have to suspend our disbelief and just accept that as a man Bond remains the same age, or gets older, then de-ages over 40 years.