An interface isn't necessary because functions defined in one mod can be used in other mods which are loaded later on. I will probably include a text file with instructions along with later versions of the mod, but here's a draft of the instructions:
Step 1: Open your mod's info.json file and add "? dark-matter-replicators >= 0.7.4" (or whatever the most recent version of the DMR mod is at the time) to the dependencies. This makes your mod load after the DMR mod which means that the replication creation functions in DMR will load before your mod does.
Step 2: Open your mod's data.lua file and add the following line to the end of it:
if repl_table then require("prototypes.replication") end
Step 3: Create a replication.lua file in your mod's prototypes folder and add functions for the replications you want to it. I haven't written the documentation for these functions yet but they're the exact same functions that are used in DMR to make its replications.
