introducing a cat to a kitten in a new environment?

[niavie]

were getting a new kitten at the weekend (6 weeks old) but my mum also wants to adopt another cat from the rescue shelter, shes 6 months old and was brought in with a shattered pelvis, shes quite nervous and shy and we dont know what she has been through before being brought to the shelter.
im just looking for advice on introducing the kitten and cat, we will be getting the kitten 2 or 3 days before the cat so she will have a little time to settle in, do you think they will get on ok seen as neither of them will be territorial? we really want them to become the best of friends and are very excited about our new family members, any advice would be brilliant, thanks.