Help, Introducing chicks to current Flock?

[dizzle's chicks]

Hi All,

I recently lost a hen (20 weeks) and I wanted to get two more chicks (7 weeks) but wanted to know how should i introduce them together without any fighting. The farm where I'm getting them at said to divide the coop and put food and water on both sides and leave them in there for two weeks to see each other but not get at each other. Since it is getting cold here is Seattle he said to close the coop door and leave them in there. Does anyone have any other suggestions in how to introduce new birds to current flock.

I current have 5 birds.
Rhode Island Red (born 6/1)
Buff Oprington (born 6/1)
Brown Leghorn (born 6/1)
Barred Rock (born 6/15)
Golden Laced Wyanndotte (born 6/8)

Planning to get
Blue Wyanndotte (born 9/7)
Black Sexlink (born 8/31)

Thanks for the help!