There's no need to convert the Forest object(s) - you can Merge wanted object(s) into a newly created scene. By having Display Influences and Select Influences selected in Merge window this will bring to your new scene also objects needed to rebuild the Forest object (this way you can easily double check that you are merging all Forest object components just by selecting desired Forest object(s)).
Also, the Forest object can be referenced (as XRef Object / XRef Scene). In case you're using the XRef Object, I would suggest you to have both Display Influences and Select Influences selected in the XRef Merge window as advised above.
Hope that helps.