introducing new lady

To be honest, I think you may be asking for trouble   After all how would you feel after coming home from a shopping trip to find a stranger asleep in your bedroom?

Is it possible to move the run?  If the hens are both in "strange" territiry it may reduce the territorial fighting.

Though I must caution you, you should really quarantine the new hen for at least two weeks, to make sure she isn't carrying any unwanted guests, or if she comes out with a respiratory infection she doesn't pass it on to yur existing hen.

Even though you are getting her from the same breeder you will never know if there is any sickness going around that should be quarantined. When you get her put her in the coup when it is dark. Be expecting some fighting and have more drinkers and feeders  doted around so they can all get to food and water. Also have plenty of hiding places so that you girl can get into and hide. I have always found that buckets placed on its side is ideal for this. Lastly get some purple spray (gentian violet) to cover up any redness after they have had a fight. If chickens see anything red they will just keep on going for it try wearing red nail varnish on you toes and you will see what i mean.

Hillfooter you will definatly need to take your boots of but wait till the weather gets warmer and a lot drier before you try it.

     
Don't forget the matching lippy 

I never go out without it
HF

I have recently tried some anti peck spray and it works really well.  Spray it on your existing hen and the new one and it will deter any pecking.  You will have to reaply after a couple of days but it should stop any bad habits forming. I think i would put the new hen in a seperate pen but in sight of the other hen for day then when it is bed time and dark put the new hen in with the other.  Let them out early in the morning and keep an eye on them, they should settle in fine. Have fun

I have to disagree with using antipack spray in this situation.

There's three reason's hens will peck each other

1  Introducing new hens to an existing flock which is established will cause the old hens to defend their territory.  They may fight pecking and flying at the intruder with their claws.  This is perfectly natural behaviour which antipeck spray won't affect.    However as in this case there is only one established bird the fighting may not be too bad.  If it is it can be viscious and injury can occur the answer is to introduce them gradually,  when they are finally integrated having two sets of feeding stations will prevent the food guarding behaviour.  Any aggression (if any) will eventually subside.

2  Pecking order establishment.  Once the new hen(s) are accepted into the flock there will be a pecking order to sort out.  The hens will do this and establish an order by pecking each other and usually this isn't a dangerous or viscious process and injury rarely occurs.  Establishing pecking order is a perfectly normal and natural behaviour which must occur in any healthy flock and you shouldn't use antipeck spray to attempt to suppress it.

3  Feather eating /plucking.  This is abnormal behaviour and must be cured by finding the cause and eliminating it.  Usually it's to do with overcrowding, boredom, incorrect nutrition or husbandry, parasite infestation or the hens not being encouraged to be active foraging animals.  Find the cause and hopefully the behaviour can be cured.  If it becomes an ingrained habit there are two ways to prevent injury and break the habit, a period of separation or a beak bit which prevents feathers being plucked.  Both these methods don't require antipeck spray which is a brute force technique which attacks the symptoms without tackling the underlying cause. 

In many years of chicken keeping I've never used it though I have very ocassionally used a beak bit on a rogue hen who has developed a habit.  I've not needed to do this for several years now and I reckon knowing how to respond and use their natural behaviour to cure them is much preferable to brute force solutions such as antipeck spray.

HF