Plote hole Alien and Aliens, solved.

Hi guys, I think I managed to close the plot hole for Alien and Aliens. My headcanon. Just tell me in the comments what you think. Hear me out...

1. The Signal So the Signal from the derelict ship was not a distress call, but a warning. And let's say a distress signal or a call for help is much stronger, a system wide signal or maybe even further. But a warning is not so long or wide spread, it's very short ranged, so you can catch it only if you are real close to LV 426. I have to address that because the derelict ship is crashed for a while, and if it was a long range signal, it would be discovered sooner.
2. The discovery of the Signal The Signal wasn't discovered by Nostromo, but an another ship. It was a cargo or tow ship, but an older class then the Nostromo. The ship was on it Route that brought it near LV 426, and then it received the Signal. MUTHER of that ship, kept the ship near LV 426 and sent a comm Massage to WY for further instructions, without ever waking up the crew from cryo sleep. WY decided, because it was a very old ship with very limited possibilities to wait for the Nostromo where they exchanged the science officer with Ash. The ship was instructed to carry on.
3. Nostromo The Nostromo so to say never received the signal by it self, it was already prepared by WY or Ash before departure to go to LV 426, of course without the knowledge of the crew. Ash was there to monitor the situation but he was instructed to not send any Comm to the HQ because of the possibility that someone could intercept the massages. So the plan was to monitor what was happening to keep the records and to store it on the safest place on the Nostromo, on the shuttle. And after everything is done, he could let the Alien on the Nostromo, take the shuttle, detach and send a rescue signal to WY, which would then send a ship to rescue him and to deal with the Alien.
4. The time gap 2122 to 2179 So because the Nostromo was destroyed, Ripley took the shuttle and disappeared, WY had no information about anything. The only information that they had, was from the ship that received the signal in first place. And because it was a ship with limitations, and limited sensors, it could only provide an approximately position of the derlicht ship. Let's say an area of 2000 square km. So WY sent a mission or 2 to find the source of the signal, but without success, because the ship was not sending anything out anymore and the position was hard to determine, like looking for a needle in a haystack. So they decided that they will build a colony there, and the main priority would be to search for the ship in the area plus terraforming. Sorry for my English.