KEEP IT AND WAIT.
I'm really interested to see how versatile brett is when it comes up to 'cleaning up' a wild beer. I've had some sours go WAY off the reservation and come back into balance when the brett finishes its fermentation cycle.
To increase chances of success, I would do two things:
1. Make sure you are mimizing oxygen uptake. Wait several months between sampling (4-6), purge the headspace (if you can), and don't move the carboy around a lot. If brett has O2 to work with, it will take the easier aerobic pathway (all while making vinegar and ignoring your butyric acid).
2. Check the acidity. Brett does more efficient work in a lightly acidic environment. Qualitatively, the beer should be lightly tart, not too sweet or too sharply acidic. The lacto will help you a bit, but depending on your primary fermentation you may not have given it enough to work with.