So after looking at it, obviously that mod has its own implementation entirely for slipstacks, but obviously you loose the stone source.
So what kind of work-around were you looking for?
Some possible ideas:
* I can detect if their mod exists, and just add stone and spoilage as an output to the slipstack as well as their stalk drops.
* I could detect if the slipstack-plant already exists, and use its loot drop as a recipe to convert the (in this case stalks) into the drop of my plant (increasing the production chain so to speak)
Currently I like the concept of the latter - you can process the slipstack stalks into the original outputs of the slipstacks from this mod.
I'll go with this fix if you don't get back to me with a better idea =)