... i would like to help with expertise on CBD oil but here in Germany it is not common ... and also i was not in the need to calm down any of my cats ... but from what i read about it - it would be worth a try - first it is natural and may help, without give it a try you will never know - but be careful CBD may have the side effect :
"there can be some adverse effects to giving your cat CBD oil, including gastrointestinal upset and some sedation, both of which can be relieved by discontinuing the use of the oil" (source:
https://www.petmd.com/cat/care/cbd-oil-cats-what-you-need-know )
So by trying you should be checking if those effect occour - (as in human medicine side effect may occour - most likle not) and so on ...
With Prozac for a short time - i really don't know if the calming effect for the short time will not bounce back to worse when Prozac is stopped giving - as last possibility maybe ... but normally i would stay away from that idea ...
Your attempts with the Feliway was without some results ?
Other question - do you use other air refreshing fragrances in your rooms ? i have seen a cat behavior specialist report here in Germany with a case with 2 cats they didn't get along with eachother and were only stressed - till the specialist told them to remove all those chemical smell sources (air refreshing fragrances) - and the situation was getting better and better ... => if when ... as hint ...
Also in your other thread you mention Akila is still not completely healthy - you noted she has
Giardia at the moment and is on medicine by now - i would assume Kebi may realized that Akila is not helthy and the behavior would be to keep her on distance ...
I've seen this behavior by cat mums and ill kitten's they separate or kill the ill one (hard nature) - can be also the cause of your issue that Kebi is just protecting herself by now.
Just try to get Akila in the first priority to complete health - solve this issue first - then take the next one - when you try too much at the same time you will loose the floor under the feet ...
Try to keep cool - get Akila first to health
when she's completely recoverd to be fit - check out how the behavior between Kebi and Akila is or have been developed ...
Take the next action after the health issue is completely solved - also check on
Giardia by Kebi too, not that she is infected also ...
fingers are crossed ...