With the new Forest Pro, comes the relocated and improved Distribution Reference objects option. You can now add multiple distribution objects and you no longer need to reselect and update in order to regen the forest objects. Great!
Also, you can now have multiple objects as reference objects. Even better!
I now want to suggest that there is a list of reference objects, so that we can see what is being used, and add/remove/disable individual reference objects as needed, instead of having to clear the entire list and re-add.