Subscription to existing users

-- HikaShop version -- : 4.5.1
-- HikaSerial version -- : 4.0.1
-- Joomla version -- : latest 3

Hi Supportteam,

We want to start with subscription on our site but we like to add a subscription to all our existing users.
On that way they won't have to buy the new sort subscription.

But it looks like you have to do that manual for every user.
Is there an option to add a subscription to a group of people?
For example to all registered users or is this possible with an import?

We have ca. 960 users