Bodhi Rook establishes Radio Contact with the Tantive whilst it is flying to Tattooine
Once the Shield gate is down the plan’s are transmitted to the tantive (Far away out of firing range) and as say the Death Star monitors that a transmission was being sent off planet because it’s on their own band width and they possibly could struggle to jam it and at that point the decision to fire on the planet is made.(Highest security Priority un-jammable signal)
Just as the plans are being uploaded to the Tantive and just as it completes sending the transmission the deathstar fires on the dish. But Too Late it got through…
Darth Vader then jumps in to the location of where the transmission is sent on the devastator.
A chase Between the Tantive and the Devastator Ensues
We See Jyn and Cassian on the beach being wiped out by the Death Star Blast.
We See the Profundity oblitterated
We see an Establishing Shot of Tattooine with a very Small Star destroyer and Tantive
We See Luke Looking through his Binoculars on Tattoine (This replaces the opening shot of Star Wars 77)
We then Cut to the Tantive shot of the explosion where it get’s hit above tattooine and being hauled into the Belly of the Devastator the Clamps attach. (the Clamps disengaging Reversed from R1.) Perhaps we follow 3p0 and R2-D2 for “they destroyed the main reactor, we’ll be destroyed for Sure” only.
An Alderaan Soldier (Instead of Death Star Plans) Has Obi-Wans Image and Location in Dune sea put on the Credit Card Darth Vader Slasher Scene ensues. As The Door Shuts the soldier shouts “Goooo!” (not Launch)
The Rebel with the Card say’s “Prepare the Escape Pods” we see the Back of Leia Only
The Alderaan soldiers in the corridor on the Tantive are waiting armed training their guns at the door the Door explodes
End Credits
Optional Insert Biggs scene on Tattooine. >>> End Credits
The Idea is that We do not follow the droids in this but when you watch Star Wars you see the Sequence from a different perspective. This is the best I can come up with.
As one Long 4 hour film it would also work this way. with the re-insertion of the opening shot from Star Wars in that Instance.
The Other Option is to move the Vader Slasher scene over in to Star Wars. and the End of the film would in that instance I guess be simply having the Devastator jumping in on the Tantives Location and the start of the chase.