You can use 3ds max Merge file command:
and then choose Your objects (it does not matter if they were xrefed or not You will find them in this dialog)
They can have cryptic name but You can find looking something like this:
If You have already setup forestpack object and want to keep it as it is in a "new / other" scene, You can just use this as a XRefScene and bind it to any helper if needed.
Hope this helps. If You still need further help please provide more details what You are trying to do.