Request for showing specific taxonomy to subscribe in specific page

I would like to have a specific subscription on taxonomy on some of the page

However existing code base :
– Only showing that taxonomy -> It will replace existing subscription, user previous subscription will gone.
(e.g User subscribed “Games, Toys” already, if user subscribe “Cars” in another page using the same email, it will replace “Games, Toys”)

– By showing all the taxonomy to subscription and I need to hide the unwanted -> Can add on the existing subscription by specific email
(It can append the existing subscription, but page loading resource will be very high due to more than 2000 – 3000 taxonomy)