Programatically update Bibliography/References CurrentList?

Hi, we are maintaining many bibliography references in a common sources.xml.

Adding new entries from the MasterList to the ActiveDocument's CurrentList is no problem in VBA or as C# WordAddIn:

foreach (Source masterSource in Application.Bibliography.Sources){
  if (currentTags.Contains(masterSource.Tag))  {
    this.Application.ActiveDocument.Bibliography.Sources.Add(masterSource.XML);
  }
}

But there seems to be no way to update citations keeping the same tag with new attributes, eg. an updated Edition number.
Any hints how this could be done?
Thanks for your help!