To add to Lumieal,
I would suggest to make the new fuse badges obtainable by trading a current fuse badge + the corresponding new pink badge.
This leading to being able to receive a War Song Badge by using a Legendary Soul Badge + Songbirg Badge or a Wildborne Badge by using a Legendary Soul Badge + Liberty Badge. This would lead to not being able to trade those badges back to the original ones, without needing to grind a pink badge again, but thats exactly the effort we have to put in anyways to get a new fuse badge.
So we could theoretically trade our new badge back into the old ones and use a new pink badge to obtain the new fuse badge again. Would be the exact same effort to get the new badge, but then we dont have to re-fuse and re-awaken it, but still invest time of getting the raw material (pink badge) if we really want a new one.