Extending The Library Palette

We have a need to have several palettes open (in seperate plugins) and each of these palettes needs to behave in a similar way to the library palette, but not the same (and all slightly different).

We will need to add items to the palette menu, as well as have slight variations in the way the previews/list are shown.

Do we need to build our own palette from scratch or can we 'extend' the library palette's functionality?

Can anyone provide some pointers with this problem, as I cannot find any similar solutions in any of the docs/forums.

Thank you in advance.