Totally agree with Lankeela.To many dogs end up in rescue because the new owners don't know what they are taking on.With Gd's it's usually they didn't realise they got so big,,doh.
Thankfully all my pups new owners had previously had GD's or another giant breed,so fully aware of their needs.
My 8th Gd was rescued.She was locked in a small 2foot by 4 foot shed/kennel.It took us many months of love and patience to get her to trust us.How people can mistreat an animal is beyond me.
At least your pup has been given a fresh start with a family that loves her.
We lost our 8th GD two years ago,and she is at rest on our plot of land.Every morning when I got to tend to the poultry I say good morning to her.
You boy will never be replaced,but your new girls will take some of the hurt away.