What exactly do you consider to be your "Campaign Message"?
Typically, your campaign tracking, using either CID or UTMs (which ever is your standard) will send relevant information in the query strings about your campaign.
In your Marketing Channels, you will create a rule such as my campaign source is "Social" so put into the "Social Campaign" channel, then you will map your full campaign code into the Marketing Channel Detail.
So now when you pull out your Marketing Channel "Social Campaign", you can break that down by Marketing Channel Detail to see the full campaign identifiers that you captured.
This should also be captured in your "Tracking Code" (s.campaign / "eVar0"), which may have a different attribution to your Marketing Channels (default 30 days), whereas Tracking Code defaults to 1 week.
I also like to track my campaign params in my own custom eVars at Visit level - then I can easily see what "drove people for the Visit" and I can always use custom attribution to look farther back if I need to.
So if you have a campaign variant for each "message", that should all be captured into your campaign parameters so that you can distinguish them.
If you are using CID, you need to make sure you and your org have a clear understanding of how your cid will be structured. If you are using UTMs, and concatenating them into your Tracking Code, then you need to determine the order those UTMs are strung together, and which UTMs will be used.. you may even need to create a new custom UTM, like utm_message that would hold more detailed information about messaging that you can pull into your tracking (if the other UTMs are all in use for other criteria)
