Is it possible to have multiple addresses compouning an unique baking node? If so, how to migrate from the current public address, moving all delegators, etc?
You can have multiple addresses baking on the same node/baker, but it is not possible to have them act as a single baker. It it also not possible to move delegators to a new address, they would have to do it themselves.
You can always move your own funds to another address, or multiple addresses, but you would just end up spreading your rolls on multiple bakers.