iCloud calendar delete/move does not delete

We share a common iCal account for two calendars (work and private), to keep track of our common work/private life.

Those two iCloud calendars sync on multiple macbooks, iPhones and an iPad. When there are changes from work, I usually delete the whole month, and insert the new one I receive (from work). I do that in iCal on one of the Macs - however, the deleted items do NOT delete on any of the other devices.

The same happens, if I move the items from one calendar, into another - it stays in the old calendar also, on the other devices.

The only way to resolve it so far, on the iOs devices, have been to disable the calendars (with delete from device), then re-enable and wait for sync.

It would be expected, that if an event is deleted from ANY of the devices, whether MB, iOs device or icloud.com, that the other devices will sync and thus delete as well? Well, they DON'T, and after change #5 in a month, the calendars tend to fill out with duplicates, and outdated revisions of events. I have to delete them manually, on EACH device - or, remove the calendar, and resync, on each device.

What am I doing wrong, or is there a bug in the system? It cannot be meant to work like this ...

Maybe this ...

I just have to reply to my own question - might I have solved it?

Usually, when I get an updated .ICS file from the company, I will use the MB iCal search function, and list all the entries for the month in question (usually, the current month). Then I Shift-click to select all the relevant month, then click delete.

After that, I import the new month, in lieu of the old one. All looks good, on that MB, but not on any other MBs, nor iOs devices (the new one is in alright, but the OLD one, which I deleted, is STILL on all other devices).

Here are two things I am trying, which MIGHT help:

1) Instead of pressing delete, using the menu, Edit->Delete instead

2) Clicking CMD-R after the deletion, and waiting for the "... Updating" to disappear at the top.

So far, it looks promising ... is that all it takes, really?

I thought those two points wouldn't be necessary?