Any suggestions on integrating a lone hen into my flock of three?

Hey everyone, I have recently adopted a two year old americauna hen "Myrtle". She was the lone survivor of a raccoon attack. I have had her for three days in a pen next to my flocks big pen. My one year old flock of three consists of Winnifred (Buff Orbington), Biatrice (Silver Laced Wyondotte) and Verna (Barnevelder). While being next to each other I did not notice any aggressive behaviors, so today I tried to introduce Myrtle and Winnie in the big pen. Immediately, Winnie became very aggressive. This was a surprise as she is generally quite docile. I've separated them, but I'm concerned about trying again because I know that Biatrice is the top hen and can be a bit aggressive. Any suggestions on what I can do to help integrate Myrtle with out her getting too beat up?

Thanks.

 

Hey, Thanks for all the advice everyone! I guess I was being a bit anxious about integrating everyone into a big happy family, mainly because I felt bad for Myrtle. I did some perusing of all the hen house pics and got some great ideas for some modifications I could make on my big run to create a fenced off section with in it...like get to know me "safely" area for Myrtle.

Thanks again.