I believe it would be much simpler to put in place some spellwork that would compliment the existing wards - where those with harmful intentions would be unable to cross the threshold, or something similar, in addition to what's already been set in place.
I do not have such a spell committed to memory at this time, but I'm certain one could either be found or created. And, of course, it would be tested elsewhere prior to use, to ensure it does not have any adverse effects.