I fail to understand why that this development could not occur offline / separate from the currently functioning system.
I'm a developer and while I know the best state of practice is to isolate layers of your system in order to be able to service and maintain them independently, sometimes in practice this breaks down. In these cases there are mitigation strategies used to bring users up to speed on the changes that are going to come and when to expect them, and how to prepare for them so users can accommodate for the changes. In the worst case scenario, things go horribly wrong and unexpected dependencies or interactions take place and then a post-mortem is needed to keep users abreast of what is happening and how it is getting fixed. This is how a company that is good with dealing with users handles these situations.
Microsoft does a pretty (sometimes a really) good job of this with Xbox and Azure, for example. Recently Gabe Aul has set a new high-bar of openness, honesty, respect and responsiveness to user feedback for the Win10 Insider program, even when dealing with many competing issues, and a wolf pack of tech press eager to criticize any MS misstep on Win10. Accelerating the Win10 fast track was fraught with peril, and Gabe did the right thing.
Family Safety team - what happened? How could you let us down so harshly, and then not give us some kind of post-mortem? People on this forum are tech savvy, no doubt, and I know that whatever you do someone will object and criticize, but erring on the side of transparency is a good trend. Follow your peer divisions there at MS, and get in front of this. Let us know the details of what happened, why and how it is going to be resolved.