Doing final testing now, but here is how my current system works. Its just some added code to DrXs modified game_relations.script.

You define the relation locks like this, using your example scenario:

faction_relation_locks = {
    ["stalker"] = { ["dolg"] = true, ["freedom"] = true, ["csky"] = true, ["ecolog"] = true, ["killer"] = true, ["army"] = true,},
    ["bandit"] = { ["dolg"] = true, ["killer"] = true, ["freedom"] = true,},
}

lock_positive_increase = {
    ["stalker"] = {["killer"] = true, ["army"] = true,},
    ["bandit"] = {["dolg"] = true, ["killer"] = true, ["freedom"] = true,},
}    

The lock_positive_increase is a way of enabling a positive increase in relations, but not a negative one. That means that, for instance, stalkers might be able to get close to factions other than bandits etc, whereas bandits wouldn't get into good standing or bad standing with the larger factions like duty, mercenaries, or freedom.

Shouldn't be too much longer til I post the script, just doing some final testing of the system.