How to dispose a message

[TheodoreCAshmore]

Hi,

I'm trying to use Fast DDS as a store of sorts, but I've found myself stuck when trying to dispose messages. I would like to be able to dispose messages that answer to certain criteria, such as those found by a specific ContentFilteredTopic. However, I am unable to understand how I can get the parameters dispose_instance needs (data and handle) if I haven't saved them when writing them.
Is there any way to do so?

Thank you for your help!