diff --git a/README.md b/README.md
index 50adbdd..ddfaaaa 100644
--- a/README.md
+++ b/README.md
@@ -82,11 +82,11 @@ const {
   MusicRecording
 } = require('./src/music')
 
-// 'member' expects an array of Parties
+// 'members' expects an array of Parties
 const group = new MusicGroup()
 group.setDescription('descriptive')
 group.setName('Beatles')
-group.addMember(man)
+group.addMembers(man)
 group.path = '<placeholder group path>'
 
 const composition = new MusicComposition()
@@ -102,17 +102,17 @@ recording.setRecordingOf(comp)
 
 console.log(recording.data())
 
-// {  
+// {
 //   "@context": "http://coalaip.org",
 //   "@type": "MusicRecording",
-//   "byArtist": [  
-//     {  
+//   "byArtist": [
+//     {
 //       "@context": "http://schema.org",
 //       "@type": "MusicGroup",
 //       "name": "Beatles",
 //       "description": "descriptive",
-//       "member": [  
-//         {  
+//       "members": [
+//         {
 //           "@context": "http://schema.org",
 //           "@type": "Person",
 //           "givenName": "John",
@@ -122,11 +122,11 @@ console.log(recording.data())
 //       ]
 //     }
 //   ],
-//   "recordingOf": {  
+//   "recordingOf": {
 //     "@context": "http://coalaip.org",
 //     "@type": "MusicComposition",
-//     "composer": [  
-//       {  
+//     "composer": [
+//       {
 //         "@context": "http://schema.org",
 //         "@type": "Person",
 //         "givenName": "John",
@@ -141,15 +141,15 @@ console.log(recording.data())
 
 console.log(recording.ipld())
 
-// {  
+// {
 //   "@context": "http://coalaip.org",
 //   "@type": "MusicRecording",
-//   "byArtist": [  
-//     {  
+//   "byArtist": [
+//     {
 //       "/": "<placeholder group path>"
 //     }
 //   ],
-//   "recordingOf": {  
+//   "recordingOf": {
 //     "/": "<placeholder composition path>"
 //   }
 // }
diff --git a/src/core.js b/src/core.js
index a8b4360..ad1901e 100644
--- a/src/core.js
+++ b/src/core.js
@@ -40,6 +40,7 @@ inherit(CreativeWork, Thing)
 propArray(CreativeWork, String(), 'genre')
 propArray(CreativeWork, new Party(), 'producer')
 propArray(CreativeWork, new Party(), 'publisher')
+propArray(CreativeWork, new MediaObject(), 'associatedMedia')
 
 // Intangible
 
@@ -121,7 +122,7 @@ function Organization (type = 'Organization') {
 
 inherit(Organization, Party)
 
-propArray(Organization, new Party(), 'member')
+propArray(Organization, new Party(), 'members')
 
 // Person
 
diff --git a/src/music.js b/src/music.js
index b221238..9d11d50 100644
--- a/src/music.js
+++ b/src/music.js
@@ -42,7 +42,7 @@ function MusicPlaylist (type = 'MusicPlaylist') {
 }
 
 inherit(MusicPlaylist, CreativeWork)
-propArray(MusicPlaylist, new MusicRecording(), 'track')
+propArray(MusicPlaylist, new MusicRecording(), 'tracks')
 
 // MusicRecording
 
diff --git a/test/fixtures/core.js b/test/fixtures/core.js
index e694086..c4c5192 100644
--- a/test/fixtures/core.js
+++ b/test/fixtures/core.js
@@ -113,7 +113,8 @@ exports.CreativeWork = {
   add: {
     genre: 'slimecore',
     producer: party,
-    publisher: party
+    publisher: party,
+    associatedMedia: [imageObject, imageObject]
   },
   set: {
     name: 'creativeWork'
@@ -258,7 +259,7 @@ exports.Organization = {
     core.Party
   ],
   add: {
-    member: party
+    members: [party, party]
   },
   set: {
     email: 'me@example.org',
diff --git a/test/fixtures/music.js b/test/fixtures/music.js
index 055e82d..f1a0133 100644
--- a/test/fixtures/music.js
+++ b/test/fixtures/music.js
@@ -73,7 +73,7 @@ exports.MusicGroup = {
   ],
   add: {
     genre: 'ska',
-    member: party
+    members: [party, party]
   },
   set: {
     email: 'me@example.org',
@@ -117,7 +117,7 @@ exports.MusicPlaylist = {
     genre: 'slimecore',
     producer: party,
     publisher: party,
-    track: musicRecording
+    tracks: [musicRecording, musicRecording]
   },
   set: {
     name: 'musicPlaylist'
@@ -139,7 +139,7 @@ exports.MusicAlbum = {
     genre: 'slimecore',
     producer: party,
     publisher: party,
-    track: musicRecording
+    tracks: [musicRecording, musicRecording]
   },
   set: {
     albumProductionType: 'DemoAlbum',
@@ -162,7 +162,7 @@ exports.MusicRelease = {
     producer: party,
     publisher: party,
     recordLabel: party,
-    track: musicRecording
+    tracks: [musicRecording, musicRecording]
   },
   set: {
     catalogNumber: '12345',