Any way to gradually relocate swallows?

I have a slight dilemma/worry…

I know a landowner who has swallows that visit and nest in their stables each year; The birds migrate every springtime and have been doing so for 20+ years.

My worry is, I know they have plans in the works to sell up the land for housing which means demolition would likely be happening within the next 5-10 years… 

I am in the process of convincing them to put up artificial nesting ‘boxes’ for the swallows, as the existing nests are now very old and falling apart, so I figured they might appreciate a new upgrade. I also had a vague plan / idea about safely relocating them, but need advice / info about whether it would actually work…

I thought that, if I could get them used to nesting in these artificial boxes / nests, I could then maybe gradually move them slightly each year until they are eventually nesting in them in trees instead… 

Year 1 &2 = Introduce artificial nests next to the old, existing nests, in the hopes that they will use the nice new ones instead.

Year 3 = Once they have fully vacated after yr 2 of using the artificial nests,  carefully unscrew the nests and move them to just outside the stables. Install a safety shelf underneath to both catch fledglings if they fall out and to sprinkle bird food on to encourage parents to stay to that area, instead of going inside the stables.

Year 4 = Once fully emptied again, move the boxes outside and near trees

Year 5 = Once fully emptied again, fully move boxes into trees.

This was my idea… But could this actually work? I know the nests would need to give the impression that they are still ‘inside’ a stable type structure, so not sure how this could be constructed… 

Also, in year 2/3 would it help to move the existing old nests they had built years ago into the artificial nest boxes to encourage them more? I know there are rules around disturbing bird nests if they are actually in / using them, but I figured if it was being done in the name of conservation / protection, since they would be torn down eventually anyway, and they wouldn’t be touched when there’s actually birds in them, then it should be acceptable…?

Any advice on helping the colony transition into trees before the stables are removed and building works start would be much appreciated! I would love to be able to preserve / protect these birds and their home as best as possible!