There is a task to send messages to about 4000 subscribers that the money on the balance has run out. This happens once a month at the same time. I see that you can only send to the topic. Do I understand correctly that I add the right customers to the “top up the balance” topic and then send a message to the group? Are there any restrictions on adding a client to a group if I do it through the API in one fell swoop? _)