What method can be used to notify friends with api ok?

Question

API

Hello.
My name is Eugene and I am a web developer. Now we are working on a program that processes user comments in albums. There was a need to send notifications to those who left comments. For example, we have 30-50 people. After processing their comments, we need to notify that their request has been processed, etc.
Please tell me what kind of api method can be used and is there such a possibility at all. The users to whom the notification is planned to be sent are the people who are in the friends or group of the one who sends.
I was looking for methods in REST, but apart from notifications.sendSimple I did not find anything. And with him it is not clear whether he is suitable for these tasks. Sending is carried out from the application, through authorization on the site. Sending is not every day, but can reach from 10 to 100 people.
What do you advise?
Thanks in advance.
Sincerely,
Evgeny Serov
[email protected]