So ive seen many pictures from oblivion with multiple oblivion girls in it with different meshes i.e. different sized breasts or simply one Exnem and another UFF. I'd like to know if it's possible to have one race use one mesh and another a different one. Becuase all i can do is change the textures. Anyone know how?

http://thenexusforums.com/index.php?showtopic=71051
In so many words, no, nothing that would look good, all the races use upperbodyfemale.nif, so changing them would change all of them...
unless, 1. you make a new folder for the skeleton 2. you duplicate (copy+paste) every animation the characters do, from weapon attacks to idle sitting animations 3. drop the new meshes in the folder with the new skeleton and animations and create a new race.
i really never wanted to do all that, chances are the pic you are referring to was photoshopped to add these actors into the picture and even better chance you will run into problems with all these files' names being the same as the original, i only tried this with a creature not a race

hm yeh i dont think its worth all that trouble. thanks for the help though

Say the case was you were using Fantasy Figures and loved it
but, you are wanting to use some of the outfits made by Hentai or for hgec, you can link the body textures in the outfit's mesh to the exnem body textures in Nifskope and doing this should make it 90% compatible with FF. if the outfit does not show any or much skin then none of this is a problem