Here is what I would do: Since this woman has never spoken of any of this to you and has only spoken positively about it to your face, I'd go and speak to her. Act like you were never told any of what her supposed plans are. Tell her your little birds are about ready to move to their coop, that you know she might have concerns and ask her if she'd like to come see them so that she will know she doesn't need to be worried about them. Include comments about the fact that you really want to make sure you aren't going to have future problems with any of the neighbors etc.
None of that may work but it's worth a shot. I'd also be checking with the authorities or the city re her history, that she's already given written permission etc. If it's true that she can revoke her "permission" at any time after the fact, and cause you to have to move your birds after you've built a coop and gotten chickens, that is ridiculous and unreasonable! I've never heard of a town's regulation's being so arbitrary and left up to individual neighor's to decide and flip flop on. I would get to the bottom of that before I went to the trouble of building a coop.
None of that may work but it's worth a shot. I'd also be checking with the authorities or the city re her history, that she's already given written permission etc. If it's true that she can revoke her "permission" at any time after the fact, and cause you to have to move your birds after you've built a coop and gotten chickens, that is ridiculous and unreasonable! I've never heard of a town's regulation's being so arbitrary and left up to individual neighor's to decide and flip flop on. I would get to the bottom of that before I went to the trouble of building a coop.