You you can only access/manage rewards created by the same clientID.
EventSub will broadcast all the reward redeems, but of course you can’t really do a catch up for redeems the clientID doesn’t own.
But the API will only let you get the reward redeems for rewards created by the clientID
This prevents two clientID’s messing with each others redemptions.
So you’d probably to delete the dashboard created rewards and use the API to create the reward. After it has been created via the API you can modify any part of the reward via the dashboard.