In case Lucky is an outside dog I would move him indoors where he can be more secure, surrounded by familiar smells. If you have to leave him alone, give him your old sweater, socks or whatever you can afford to be chewed up but has your scent on it. Play the radio or TV.
When our old dog died the younger ones (oldies themselves) went on a hunger strike for 5 months. One of them I had to prevent her from jumping in his grave during burial. I had a heck of a time keeping them alive. If I had let them they would have died. They lost every bit of life in them. So we went fun places, made them the best meals and eventually they returned back to their normal selves. Also I didn't baby them to prevent more needyness. I don't think adding another dog during that time would have helped them but more confused them. By the time WD came along they had been OK for several months.
I hope your home will be happy soon. It is so hard missing them and especially if the other dogs suffer as well.
I never knew what an impact the death of a pack member would have on the other dogs.
Deja, GSD, sable WL, female, born 11 / 2013
Cam, Rough Collie, sable, male, born 8/2015