When I ask my servitors to research something, I basically tell them to go look everywhere and everywhen. While brainstorming ubiquity, I had this constant notion in my mind that they should be able to multiply fast enough (hence the instances being able to create new instances) and without draining my servitors, so that my servitors could send an unlimited numbers of instances everywhere and everywhen. I did not explicitly write it, but I strongly and repeatedly conveyed the idea to my servitors and it’s underlying the ubiquity skill they researched.
So, if we did it right, there should be no limitation on the number of instances or the amount of multi-tasking. So yeah, one fae could work on an entire family, and, theoretically, indeed, on many many more people. Now, free will and all should be taken into consideration, of course 
But that’s the theory. And it kinda seems to good to be true. I mean, I’ve been working with my servitors for about 2 months, and I already made them this powerful ? 
So, for now, I reserve my judgment on how many/how much they can do. Time and experience will tell.
…
Actually, I just debriefed my servitors, and there are indeed problems that need to be solved. They are working right now with about 15 instances, and that’s enough to cover the main tasks I’ve been asking them to do, but it’s clearly not enough for all I have in mind for them.
From what I gathered, the instances created by instances are part of the problem, and the instances are somehow taxing on my servitors. I know that they went pretty wild at first and created way more instances, but obviously they had to be more reasonable when they ran into troubles.
I’m gonna investigate and see what they can do to solve all this.
I’ll keep you posted and I’ll update my first post when needed.