Quote: This is a tuffy....removing her from the flock to feed her up and give her a break might be a good move, she will get to eat and maybe gain some confidence.
BUT re-integration will be another problem and could make the picking on issue worse.
I wonder if the other bird that died was ill and this one may be ill too...flocks will try to drive off a sick bird.
There are a couple ways to deal with it.
Put her back in with the flock and provide multiple feed/water stations, places to 'hide out if line of sight' but not dead end traps and extra roosts get up and away from aggressors and let her find her way. Squirt gunning any aggressors can help but takes a lot time to monitor.
Or....this takes time and energy too:
Create separate but adjacent areas in coop and run where they can see but not touch each other.
Let her live there for a week or so to gain some weight and rest, feed treats along the barrier so they get used to eating near each other.
This will allow the spitz to make the area her own.
It's all about territory and resources(space/food/water), this time you will be putting a 'new' bird into 'her' territory and it's only one so it evens the odds in a 'fight'.
So then put one of the more docile of the flock in with her and see how it goes, remove bird back to flock if overly aggressive and try another one.
Mix and match them like this until you get someone to get along with the spitz, then add an additional bird in with them.
You are trying to create some camaraderie or a 'unit', once the spitz has some 'friends' you can try to rejoin the flock together.
Just some ideas....or you could just get rid of the spitz and leave the rest of the flock to exist as they are.