if i want to place textures from multiple objects all on to one bitmap say 1024X1024 do i need to attach all these objects together ?
I was just talking about the texture itself. How you've organized the model in GMax is of no relevance at all to your work in Photoshop (or similar).
I was just implying that you shouldn't throw away the wireframe layer in the master texture file while not filling it up with n+1 wireframe layers.
Here's a shot to illustrate what I mean. All (major) parts I've ever unwrapped for use on textures are contained in a single wireframe layer.
It's actually more a matter of orderliness and practicability than absolute necessity.
or is there a way of unwrapping multiple different objects on to one sheet?
I'd do it one by one. Start off with the most important parts (fuselage, wings) and work your way down from there until the texture file is filled. Then move on to the next one.
Is this what you mean here when you say fill up the texture map ?
Yes. If you use as much of a texture file as possible, you can save disk space and performance in FSX.
if so how is the single texture sheet then applied to multiple objects in max how will max be able to re map all thoese texture from one sheet to multiple objects if the sheet was created in photoshop from layers of uvw templates or baked texture bitmaps?
That's what materials are for. They basically define surface properties with a bunch of settings and the texture file you've created in Photoshop.
You can do anything you want with the bitmap. I, for example, use red stripes or checkers to check e.g. if the left and right fuselage are correctly mapped and the textures precisely meet up at the seam before I go and paint the real texture.
Something like this:
also if i want to bake multiple texture from multiple objects on to one single sheet what is the correct method for doing this?
Whatever the "unify layers" in your image editing program is called.
Really, it's all very easy. Just fuss around a bit in Max or Photoshop and you'll soon have your own method of doing things.