Merging items separately only by its ID.
example: iceandfire:silver_ore=silentgems:silver_ore (excluding thermalexpansion:silver_ore, so the thermalexpansion silver ore is not being merged)

This'll be in the next version (up momentarily).
To add an item conversion simply add another line to the config with the following format: modid:item>modid:item where the input is on the left and output on the right. Tag conversions will work as before (with =).