In First Contact we see their Earth 'borgafied' after the sphear opens its temperal portal, so clearly the altering of history effected their existing timeline. That was what I was thinking of, clear examples where we literally see the timeline has changed.
In City on the edge' we see the crew stranded on the planet as the Enterprise and federation no longer exist.
I actually didn't count ST4, forgot about the TA formula. However, they were not aware of the formula's origins, and them giving it to that guy could very well have been how it always happened. They point out as much in the film. This is how I think time travel should work, and was how they portrayed it in;
Times Arrow. Here the actions of the crew in the past were already a part of history. Guinan had been aware of the events for hundreds of years.
In City on the edge' we see the crew stranded on the planet as the Enterprise and federation no longer exist.
I actually didn't count ST4, forgot about the TA formula. However, they were not aware of the formula's origins, and them giving it to that guy could very well have been how it always happened. They point out as much in the film. This is how I think time travel should work, and was how they portrayed it in;
Times Arrow. Here the actions of the crew in the past were already a part of history. Guinan had been aware of the events for hundreds of years.





I'd have to check on those. They all sound plausible! To tell you the truth, I had one episode in mind that I know the guards are there and I had a thought there were others, but I wasn't sure which!



