Showing free/busy time

I have code that creates calendar entries in individual.nsf files (not using LotusScript - using a C API program). I try to manipulate whether the entry is shown

as busy by setting the “BookFreeTime” property. However

that does not seem to have any immediate effect. It is

necessary for the user to open the entry and re-save it,

in order for other users to accurately see the status. I assume that the Notes client is updating something on the server that is used to store shared calendar information? If so, how can I do that with my C program? Or is there some script I could run on the client? How would it work?