I want to add a Esri personal or file geodatabase into a existing geodatabase which is an enterprise SQL SDE environment. Is this possible?
It is possible using the append tool or the Import from Geodatabase (Single) or Geodatabase (Multiple) but you would need Desktop Standard or Advanced in order to edit or create feature classes within the SDE geodatabase.
There are many ways to migrate data from single user (i.e. file geodatabase) to a multiuser geodatabase. Please see the following help topic for several ideas.
Retrieving data ...