Sorry for the loss and my opinion may be a tad different, but logical to me because we keep our chickens as livestock and not pets though we do name many and think the world of them.
There is a time to kill the dog and a time to try to deal with a mistake a neighbor made and is trying to make good.
Right now I would accept the replacement birds and make it very clear next time will be the last....
The replacements would be same age that were killed by their stinking dog they were not responsible enough to keep at home.
Dog comes back it is then time to shoot it and the neighbor is much more likely to understand why as will be authorities if he makes a report.
Just how we decided handle it with a neighbor dog and it has not been back, but the ones I have had to dispatch were strays.