That's good all is calm now. Hopefully mama and ducklings will have a few weeks to seal their bond and when they are finally put out with everyone the flock will accept them. Be sure ducklings can't slip through fencing and end up a play toy for new pup.
It could be the other duck caused it by getting to close and mama tried to run her off. Ducklings get trampled in the process. If she isn't making the others get out from under her and is sitting tight they maybe okay just keep a close watch on how she is acting. My broodies do not like any...