diff --git a/docs/model.md b/docs/model.md
index d61b805..ed3c8c1 100644
--- a/docs/model.md
+++ b/docs/model.md
@@ -34,6 +34,7 @@ ProviderType {
 Channel {
     string id "PK"
     string name ""
+    string parent_channel_id "FK"
     string created_at ""
     string deleted_at "IDX"
 }
@@ -75,11 +76,12 @@ User ||--o{ ChannelUser : "1"
 ProviderTypeUser }o--|| ProviderType : "1"
 
 Channel ||--o{ Message : "1"
+Channel ||--o{ Channel : "Nest(parent_channle_id)"
 ChannelUser }o--|| Channel : "1"
 
 Message }o--|| User : "1"
 Message ||--o{ Reaction : "1"
-Message ||--o{ Message : "1"
+Message ||--o{ Message : "Reply(reply_to_id)"
 Message ||--o{ MessageReaction : "1"
 Message ||--o{ MessageReaction : "1"