Mothering instincts or not

I have two cats named Lily and Daisy. Lily was the first that I adopted from my local veterinary office. When Lily was about a year old I decided that she needed a friend as I thought thiat she maybe lonely when I was at work all day. I adopted Daisy as a kitten from the same veterinary office. When I brought Daisy home it was hatred at first sight for Lily. I kept Daisy in a large enclosed cage when I was not home for the first few weeks for Daisy's protection as Lily kept tormenting her by hissing at her and trying to attack her and all Daisy wanted to do was cuddle with Lily. However that all changed when Daisy was 4 months old and got very sick. It turns out that Daisy was born with the herpes virus. Almost as soon as Daisy got sick Lily's mothering instinct kicked in. Lily went from tormenting Daisy to becoming a mother to her and took to cuddling her and cleaning her and allowing her to be on the top platform of the cat tree. When Daisy recovered from that out break of herpes Lily went back to her old ways of tormenting Daisy (although not as severe). This occurs everytime Daisy has an outbreak. 6 months ago Daisy was also diagnosed as epileptic. When Daisy has a seizure Lily runs over to her and stays with Daisy until she has recovered from the seizure, then she goes back to her old ways. I sometimes think that this is just a show on Lily's part and that deep down Lily really loves Daisy but doesn't want me to know in case I get ideas about bringing another cat home.