Hello Bicycle_micycle
Halftax and Halftax Plus are two completely disjont things. You can have either one seperately or both at the same time. In my opinion, the naming Half Fare Plus is just confusing and doesn’t describe the offer well. So yes, you can get a Half Fare plus at any time.
BTW, I consider it polite to open a message with greetings. In the community, you get advice from volunteers.