Adding functions to generic package

[Preben Randhol <randhol+cla@pvv.org>]

Hi

I'm using the charles library which has a generic list package. I would
like to add two procedures Randomise and Move so that all my lists can
use them. I cannot modify the library itself, so what choices do I have?
Is making a child package the only way to add the procedures in a
generic way?

Thanks in advance 

Preben