Block time on my other calendars

This one may be too hyper-specific to my needs, but you don’t get what you don’t ask for.

I’d like some functionality that would allow me to automatically add an appointment to other calendars when I put an event on a calendar. To make that (I hope) more clear…

I have multiple work calendars for different clients. When I schedule time for a meeting in one calendar, I’d like to be able to configure an appointment that would replicate to the other calendars, effectively blocking that time off for all clients. In a perfect world, I would be able to set some parameters on that automatically created appointment like the Subject, availability (Free, Busy), visbiilty (Private flag), and such.

Alternatively, some sort of scripting/macro language where I could automate this for myself would work nicely as well.