I’m afraid you’re going to have to return them then, unless you are unbelievably lucky. This feature has been being requested for years, and nothing has come of it. In the early days, there may have been the odd comment about it being a good idea, and that they would look at it, but more recently, at least for a year, they haven’t commented at all. Amazon does not allow Blink to discuss their road map now, so you won’t even get a comment such as, ‘coming in 2 months’.
That being said, you could hold onto them and hope, but it would be nothing more than that, or settle for them as they are, and work around the issue, or you could return them whilst you have the opportunity to do so and whilst it’s relatively hassle free.
I don’t think it was ever intended to be anything other than a simple single user, monitor my door or back yard for motion type product, with one user controlling the app. Maybe the partner too, but then why would people not be prepared to share the log in details with their partner? The extended use possibilities that other users see, such as yourself, would probably represent a tiny proportion of their sales, which their data will tell them about, and as such it probably gets a low priority, despite the odd person here and there shouting, this is a ‘MUST’ have, or this ‘NEEDS’ to be an option.
As an example, I now have four sync modules, and seven cameras, across two different sites, so my system is growing but I have no requirement at all for additional users, or customised access levels, and I suspect I represent the vast majority of the user base. Indeed, looking at your use case scenario, you mention using it at the office, which is obviously a commercial environment and this isn’t even supported in Blink’s terms and conditions, indeed it is specifically precluded.
Would it be a nice addition, sure, is it NEEDED, obviously for some, but not for Blink, or it would have been done.