how to merge ml inferenced grammar and manual grammar rules

[r0ller]

It needs to be figured how to protect manually crafted grammar rules from merging with inferenced ones.

Example: grammar rules to process logical expressions are crafted carefully to be able to build appropriate semantic dependencies based on them. In order to protect them from merging with ml inferenced rules it shall be possible to indicate that new rules based on the terminals of such protected rules shall not be merged in the grammar.