Campaign Tags provide powerful flexibility for custom reporting. Simply select the keyword that you’ve tagged your campaigns with. Custom Reports will automatically select those campaigns you’ve tagged with the keyword — so you don’t have to.
This section instructs you how to create your Campaign Tags and apply them to your campaigns. Read the section in Custom Reports to learn how to use them for reporting.
Scenario 1:- While campaign tags will add to a previous sends in a recurring campaign?
Answer:- No, it won't be associated with previous sends.
Scenario 2- If a campaign tag is applied in the middle of the campaign will it apply to the child campaigns?
Answer:- Yes, that's right.