How to deter barn swallows from nesting We've allowed 50 but no more!

This link has several options:

hang a paper lantern. Bugs and birds will think this is a wasp nest and keep clear of the area. The question is.. what do you have planted near by that is attracting them? Hawks frequently nest near snakes as that is what they feed to their hatchings. The same goes for your nesting birds.

Once they start, spray the area with a pressure nozzle hose

take a broom and knock them down at soon as you see the first glob of mud ... don't let them get ahead of you;

I had a swallow building a nest on my apartment deck....he would dive bomb me whenever I went outside. The maintenance man got rid of it (wasn't completely built) and the next day, the determined swallow started building another one....took a swish of the broom to stop him....and that was the end of it. Next year I didn't notice any nests. I had cable wires going across my deck and birds used to roost there, making a big mess....learned if I stuffed balled up newspaper between the wire and wall...problem solved. No room for them to roost.

We'll do all of the above. First, we can knock down the mud legally before eggs are in the nest but we will need to let them hatch in the ones that we allowed. I found a wood nest box for barn swallows online that sold for $40 (one box). At the rate of the houses needed this year, we would be spending thousands so we will work on an alternative for next year. Not sure why they don't build on the barn that's about 50 yards away from the house but they never have. I tried to get an owl or hawk in town but no one sold them. Word online says they don't always work. My husband put up metallic strips along the eaves but they seem to like it. Next year we'll keep a boundaries :)