Should I move my 4-Line Damsel

My girlfriend had an emergency, and I had to take her 4-Line Damsel before it died.

I put it in my 20-tall with a Yellow Tail Damsel and a large Ruby Scat.
The Yellow Tail is just a bit larger than the TINY 4-Line, and has been there for about 6 months while the Scat is like 8X the size of both and has been there for about 2 months. The scat is SUPER calm and leaves everyone alone.

My prob: The Yellow Tail is really picking on the 4-Line, and keeping him up in the corner, even though I've read that Yellow Tails are the least aggressive damsel, while 4-Lines are one of the most aggressive... so I thought it'd work.

Option 1: Take Yellow Tail to LFS... cause I like 4-line better
Option 2: Move 4-Line or Yellow Tail Damsel to 60g where I have...
-Medium Yellow Tang (kinda aggressive now)
-Large 6-Line Wrasse
-2 Paired Ocel. Clowns
-Lawnmower Blenny
-Fire Shrimp

I'm worried the Yellow Tang will kill (killed a small wrasse months ago), or the damsel will pick on my lawnmower... not really worried about much else... 6-Line is pretty chill and keeps to his own, and clowns keep to their anemone.

SUGGESTIONS????

 

rearrange the rocks and hiding places to create new territories for the fish. the blue yellowtail will not recognize his old territory, and be less defensive, aggressive, and territorial towards the other damsel. it's a natural pecking order process though, and it's gonna happen.

 

My advice to you is to return the 4-stripe damsel(humbug) as you will encounter bigger problems in the future if you plan on adding any other type of livestock! They will become much more aggressive than the Yellow-Tail...trust me!

 

humbugs get very aggressive, I would get rid of it.