diff --git a/group/add-member/README.md b/group/add-member/README.md
index ecb65de..34d1a9f 100644
--- a/group/add-member/README.md
+++ b/group/add-member/README.md
@@ -2,13 +2,19 @@
 
 :warning: schema.json is generated so don't modify it directly
 
-This is about adding people to your group
+This is about adding people to your group, or 
+
+
 
 ```js
 var content = {
   type: "group/add-member",
   version: "v2",
   secret: "3YUat1ylIUVGaCjotAvof09DhyFxE8iGbF6QxLlCWWc=",
+  oldSecrets: [
+    "apple1ylIUVGaCjotAvof09DhyFxE8iGbF6QxLlCWWc=",
+    "potatoylIUVGaCjotAvof09DhyFxE8iGbF6QxLlCWWc="
+  ],
   root: "ssb:message/classic/THxjTGPuXvvxnbnAV7xVuVXdhDcmoNtDDN0j3UTxcd8=",
   creator: "ssb:feed/bendybutt-v1/VuVXdhDTHxjTGPuXvvxnbnAV7xcmoNtDDN0j3UTxcd8=",
   text: "welcome keks!", // optional
@@ -37,7 +43,9 @@ var content = {
 
 Notes:
 
-- `secret` is the symmetric key for the group
+- `secret` is the symmetric key for this epoch
+- `oldSecrets` is an array of all secrets of all predecessor epochs to this epoch, all the way back to the root epoch. Should be undefined or at least empty on re-additions.
+- when initially adding someone to a group, there should be one add-member message per tip epoch. this is to make it clear to the people in that epoch what the members of that epoch are. this is also why `oldSecrets` only should contain secrets of predecessor epochs, not of parallel fork epochs
 - `root` is the same as `tangles.group.root`
   - the redundancy is here to make it more obvious which root you should be using the compute `group_id`
   - in the future our tangles may be _cloaked_ which means this key would become more important
diff --git a/group/add-member/v2/schema.js b/group/add-member/v2/schema.js
index 8c5533f..361f933 100644
--- a/group/add-member/v2/schema.js
+++ b/group/add-member/v2/schema.js
@@ -32,6 +32,11 @@ module.exports = {
       pattern: '^v2$'
     },
     secret: { $ref: '#/definitions/secret' },
+    oldSecrets: {
+      type: 'array',
+      items: [{ $ref: '#/definitions/secret' }],
+      minItems: 0
+    },
     root: { $ref: '#/definitions/messageId' },
     creator: { $ref: '#/definitions/feedId' },
     text: { type: 'string' },
diff --git a/group/add-member/v2/schema.json b/group/add-member/v2/schema.json
index e5dca17..93cdbc6 100644
--- a/group/add-member/v2/schema.json
+++ b/group/add-member/v2/schema.json
@@ -22,6 +22,15 @@
     "secret": {
       "$ref": "#/definitions/secret"
     },
+    "oldSecrets": {
+      "type": "array",
+      "items": [
+        {
+          "$ref": "#/definitions/secret"
+        }
+      ],
+      "minItems": 0
+    },
     "root": {
       "$ref": "#/definitions/messageId"
     },
diff --git a/test/add-member.test.js b/test/add-member.test.js
index 6cb3346..f140b0f 100644
--- a/test/add-member.test.js
+++ b/test/add-member.test.js
@@ -13,6 +13,7 @@ const Mock = (overwrite = {}) => {
     type: 'group/add-member',
     version: 'v2',
     secret: Secret(),
+    oldSecrets: [Secret(), Secret()],
     root: groupRoot,
     creator: FeedId(),
     text: 'welcome keks!', // optional
@@ -95,5 +96,13 @@ test('is-group-add-member', (t) => {
     '%shGMltJNglMNLpxdnDGz/Y+j6HukBelnCS84D+GR2DM=.sha256'
   t.false(isValid(sigilLink), 'fails if a link is a sigil link and not a uri')
 
+  const noOld = Mock()
+  noOld.oldSecrets = undefined
+  t.true(isValid(noOld), 'can have missing oldSecrets (e.g. on re-additions)')
+
+  const emptyOld = Mock()
+  emptyOld.oldSecrets = []
+  t.true(isValid(emptyOld), 'allows empty oldSecrets')
+
   t.end()
 })