Disable send update to all attendees VSTO - vsto

Question

I'm using VSTO to develop add-in for Outlook.
When using Send method of MeetingItem (AppointmentItem), how can I disable Send Update to All Attendees popup? It always show when I call Send of existing meeting.
I only found ForceUpdateToAllAttendees property but it make the update send to all attendees, that would be wrong if user don't want to send updates to all attendees.
EDIT:
This is my code
void Application_ItemSend(object item, ref bool Cancel)
{
var form = new SC01(item);
form.Show();
Cancel = true; // prevent mail sending
}
...
in SC01 form:
private void btn_OK_Click(object sender, EventArgs e)
{
var meetingItem = _item As MeetingItem; // _item is private field of SC01
meetingItem.GetAssociatedAppointment(false).Send(); // this Send() will make sending option (to update attendees only or to all attendees
}

Answer 1

sorry I was away some days. I think I have the solution, althuogh I only "speak" vba - but in the end it is all the same...
leave away the line:
Cancel = true; // prevent mail sending
and also the line:
meetingItem.GetAssociatedAppointment(false).Send();
as far as I know the item will not be sent anyway as long as the form is not hidden again.
I hope this works!
Max

Answer 2

just had another idea that should solve your Problem:
void Application_ItemSend(object item, ref bool Cancel)
{
var form = new SC01(item);
form.Show();
'''next line is new and prevents the first popup
item.ForceUpdateToAllAttendees = TRUE
Cancel = true; // prevent mail sending
}
... in SC01 form:
private void btn_OK_Click(object sender, EventArgs e)
{
var meetingItem = _item As MeetingItem; // _item is private field of SC01
'''next line is new => popup Comes now
meetingItem.ForceUpdateToAllAttendees = FALSE
meetingItem.GetAssociatedAppointment(false).Send(); // this Send() will make sending option (to update attendees only or to all attendees
}