Custom event to indicate an image belongs to a conversation

I want to upload images and reuse them in a conversation, i.e. the bot must be aware of the image name. How would I do that without sending a text message and triggering a bot response? Should I use a custom Tracker event, should I use a slot event that I inject, or should I send a user message without text and only with metadata?

Any ideas?

There are several earlier posts on this topic. Check here and here and here

Thanks, but I am aware of how I can store the images/files.

My question is how Rasa should know that these images belong to a conversation. For instance, I could upload an image and after the successful upload, I send a message with an empty text but metadata that holds the path to the image. I would could modify the frontend so that the message does not show as a user utterance but as an icon or similar. Another way could be to inject a custom event into the tracker directly to avoid that Rasa predicts the next action something. Then the image would be connected to the conversation via the id and I could retrieve the event when the user asks for it.