SIAD said:
It is possible that everything you say is true. Then could you explain me well the 4 Time Lines? How did they originate?
Following this theory, this is how I think everything happened:
History A1 - Son Goku returns to Earth and defeats Freeza and Cold. The Saiyajin then dies of a heart disease and the androids # 17 and # 18 dominate the events of A1, forcing Trunks A1 to travel to the past (pretty much a parallel of Mirai Trunks' timeline). The rest of the events are unknown.
Past Alternative A2 - Trunks of the future A1 defeats Freeza and cold. However this is still not enough to prevent Son Goku's death, the androids sow the destruction, but due to unknown events they are somehow disabled (some people saynit's due to a remote control). Pass 23 years from the incubation of Cell A2 and he starts his search for the androids. The A2 Trunks decides to travel to the past to change the events, however chooses 1 year before the arrival of Freeza and Cold for whatever reason. With no knowledge that there was a third android (Cell), the Trunks A2 is defeated easily by Cell A2 and this latter returns to the past to attain his perfect form. In this example the Cell A2 will travel to the past alternative B2 (explained below).
History B1 - Son Goku returns to Earth and defeats Freeza and cold. The Saiyajin dies of a heart disease and the androids #17 and #18 dominate the events until Trunks B1 travels to the past. With his return after the triumph in the past B2, the trunks B1 destroys the androids #17 and #18 and years later defeats the Cell B1, preventing him from returning to the past. In this line of events the Cell B1 is aware of the existence of Trunks B1, but the data itself is unknown.
Past alternative B2 - the Cell A2 travels to the past without being aware of the parameters of the journey and reaches this new past 1 year before the arrival of Trunks B1. Then, it happens the history portrayed in the manga, the Cell B2 is destroyed while still in larva, the Cell A2 reaches his perfect form and is defeated by Son Gohan in the Cell Games. The past alternative B2 is saved and Trunks B1 returns to his time and saves it as well.
Also, it's worth noting that, in the future Cell's timeline, Goku probably didn't die from a heart virus (considering that the future Trunks who came from yet another timeline should have obviously handed him the medicine)... he likely died because of the androids, so as far as the Trunks from Future Cell's timeline knows, Goku wouldn't be this game-changer as it was portrayed by Bulma in Future Trunks' timeline (as well as in the timeline of the future Trunks who went to future Celk's timeline)... so that could explain why that Trunks from Cell's timeline didn't try to travel to the past until he had already killed the androids... he didn't travel to the past to hand Goku the medicine, as the Goku from his timeline dies in another way. So the Trunks from Cell's timeline obviously perceived Goku in a different way compared to the aforementioned Trunkss.
Moreover, there isn't a need to have a timeline to where the Trunks from future Cell's timeline travelled to... that isn't hinted at the manga, and he could very well have destroyed the androids from his time without having to resort to traveling back in time... maybe the Trunks from Cell's timeline also found the scripts in the underground laboratory somehow, dunno.
A chart made from a member of Kanzenshuu: