[{playlist:{userName:"user-name",userId:"user-id",playlistArray:[{playlistName:"playlist1",playlistSongs:[{track:"",title:"",duration:0,uri:""},{track:"",title:"",duration:0,uri:""},{track:"",title:"",duration:0,uri:""},],},{playlistName:"playlist2",playlistSongs:[{track:"",title:"",duration:0,uri:""},{track:"",title:"",duration:0,uri:""},{track:"",title:"",duration:0,uri:""},],},],}}]

db.collection.update({},{"$push":{"playlist.playlistArray.$[pl].playlistSongs":{track:"sometrackinfo",title:"sometracktitle",duration:123,uri:"sometrackuri"}}},{arrayFilters:[{"pl.playlistName":"playlist2"}]})