Neither of you can read the other's mind, but you seem to be trying a little bit. The fact that it bothers you implies that you think there's some sort of negative intention or action behind her switching out the towel dispensers. I don't know nearly as many of the details as you do, of course, but perhaps you can consider the possibility that there is a specific reason that the towel dispenser you selected will not work for her purposes as well as the one she selected. Perhaps she needs a motion-activated dispenser and yours are not; perhaps motion-activated is not ideal for whatever reason and she needs a manual one. Given your confidence that this project is going to be an overwhelming success, perhaps you can direct that confidence into knowing that your DIL likely has a specific reason she needed the towel dispensers she selected. But, as others have said, this isn't really about the towel dispensers. You didn't say in your post whether she's shown and/or stated her appreciation for your huge level of support throughout the process, so it's impossible to say from the outside looking in if this is more about feeling taken for granted. It sounds like this may be just a "final straw" kind of thing and it would have happened with something else even if you'd picked the "right" towel dispensers. If that's indeed the case, it's totally up to you but realize that there are ways to have a conversation about that without having to "confront her" as you put it. You've put a TON of work into this, it sounds like, and you likely have some well-earned sense of ownership. Pitch it as just trying to understand where each other is coming from, maybe even just a look at what role, if any, she may need/want you to have going forward (and that you're willing to do).