Hello and welcome to BYC! 
Glad you joined.
The easiest way to integrate new chicks with a lone adult hen is to brood the new chicks in the coop in a secure area where both parties can see and hear each other but not touch each other. Then when the chicks are about 3 to 4 weeks old you fashion a small door so the chicks can get out but the hen cannot get in and you let them start to integrate that way. By the time the chicks are 6 to 7 weeks old they will be roosting with the hen.
I would introduce at least two chicks to her.
Is your coop large enough to support three chickens? Is your run predator-proof with a solid roof? Three chickens will need about 12 sq ft of space in the coop that does not include the nest box area.
Glad you joined.Not really.
The easiest way to integrate new chicks with a lone adult hen is to brood the new chicks in the coop in a secure area where both parties can see and hear each other but not touch each other. Then when the chicks are about 3 to 4 weeks old you fashion a small door so the chicks can get out but the hen cannot get in and you let them start to integrate that way. By the time the chicks are 6 to 7 weeks old they will be roosting with the hen.
I would introduce at least two chicks to her.
Is your coop large enough to support three chickens? Is your run predator-proof with a solid roof? Three chickens will need about 12 sq ft of space in the coop that does not include the nest box area.
to have you here with us. Enjoy your time here at BYC!
You've been given some great advice already, but to answer one question you had, the breed doesn't matter when adding new birds, they don't recognize each other that way. Its all pecking order stuff, as alone as she is, she will still stand her ground as leader and squabbling is inevitable. Take your time mixing in new birds from behind a cage or wire fence, and it helps to mix in birds over 3 months of age. Good luck!
