Thanks for contacting us. I'm afraid that when working in Custom Edit mode the areas list is disabled as it has no effect, even using the new effects feature. However you could drive the animations using a grayscale map. To do this:
1 - Apply a surface to the FP object. Forest will adopt the UVW coords of this to position the map.
2 - In the Animation Rollout, change the mode to Frame From Map
3 - Set the Start
frame to encompass the animation on your source object.
4 - Add an animated greyscale map to the Map slot
. For example you could use a Gradient ramp and animated the Offset
Now when you animate the map it will control the animations.
I've attached a file to illustrate this approach, I hope it is of some help, please let me know if you have any further questions.