I have the same problem, but in reverse! My hens are very happy to race out into the garden, but I have to bribe them back into the coop with chicken crack (scratch feed—which I don't give them any other time.) This is only if I need them in before the sun goes down; otherwise, they go in on their own.

If it gets brutal (you see blood!) try separating the new one during the day, but just via a fence, so they can all still see each other (a portable dog fence is perfect for this.) They will work it out in time. In the future, add to your flock in pairs or threes. Less "ganging up" behavior.

I've gotten my hens (mostly older pullets or point-of-lay) from you all for years. I keep a largish-size flock, between 15 and 20 girls, replacing them in twos and threes as necessary. I love having a good mixture of (basic) breeds at all times—which can get confusing as to names, so I just pass down the same names within each breed. My most successful—in terms of longevity and egg production—are barred rocks (Patience, Sarah), black sexlinks (Billie, Bessie, Bonnie), and easter eggers (Mary, Martha, Maggie). You can't beat a healthy RIR (Polly, Nettie, Annie), and I've had good results with black australorps (Lena, Zora), although I don't have any currently. I have had only so-so success with golden sexlinks (Puff, Spot) and new hampshires (Winnie, Connie). I used to sneer at Leghorns (I mean, white eggs!) but my two old girls (Sally and Jane) are still champion 6-eggs-a-week layers. No buff orpingtons for me, please—frequently broody and constantly cranky. Their name(s) are lost to history! Thank you all at D2D for living your dream and helping me continue with mine for so many years!