How can we add a button for "add a new sub-category in this category" in frontend using k2 ??
The frontend users should only be able to add/see categories below their allowed categories.
When a user clicks this button he should see the form just like we see in backend of k2 for adding a subcategory.

Hello,

Unfortunately this is not possible with K2 v2. A user can only add items in the front-end.