It seems from what I've read in the help index it is not possible to have two editable symbol collections in one document. I can import local and network symbol collections but the symbols within them can not be edited.
I just want to check that i haven't missed something.
I have a lot of symbols, about 30, and I am about to add 30 completely different symbols and it would be nice to be able to keep the two groups separate and easier to manage that way.
I haven't used symbols a lot, but I believe it is possible to also have symbols outside the document, in a symbol library.
The instructions are in the help file but I can't remember whether a document containing symbols from a library will automatically update when the library symbols are changed.