A perfect answer to your question can be found in the Stack Overflow post
How to post calendar event to participant's specific calendar.
Short answer : No go. There are workarounds, but they are just as bad as the
original problem. You may be better off adding rules to everybody's
default calendar to do the job.
Here is the answer reproduced :
Google Calendar, regardless of the API or the language you use, is
based on the iCalendar standard, which, from my readings of it, does
not have the concept of "Invite a participant and post event
invitation on this specific calendar of that participant." If I'm
wrong, the quickest way to get your answer and prove me wrong is to
find evidence of such a feature in the iCalendar documentation.
I thought I had a workaround, which is "Hey, if you have access to
person-B's calendar, why not just create the event on their calendar
and add person-A as an attendee?" I did this by sharing one of my
sub-calendars of one of my Google Calendar accounts with another. But
sure enough, you get the same problem in reverse. Now person-B has the
event in the right place, but person-A has it on their default
calendar.
So depending on which is your "primary" account, you may want to go
that route, but I'm guessing you find that about as appealing as what
you're dealing with already.
The only other workaround I found (which was not all that great), is
you can access Person-B's calendar and copy the invite to another
calendar (the one you want), and then delete it from the main
calendar. This will work (I tried it), but obviously it's not as
graceful as what you had in mind.