If you must take ducklings from their mother, it's important to do so carefully and to provide them with proper care. Ducklings should be kept in a warm, draft-free environment and provided with a safe place to hide. They should also be fed a diet that is appropriate for their age and development.
Once the mother duck has hatched all of her eggs and separated the other ducklings, it may be possible to reintroduce the ducklings to her. However, this can be a difficult process, and there is no guarantee that the mother duck will accept the ducklings. If the mother duck rejects the ducklings, you will need to continue to care for them yourself.