Updating Mongoose Subdocument collection

Updating Mongoose Subdocument collection

I have the following mongoose Schema's defined...
var BlogSchema = new Schema({
content: String,
comments:[CommentSchema], //embed the comments
owner: {type: ObjectId , ref: 'User'}
})
var CommentSchema = new Schema({
commentContent : String,
commentPostTime : Number,
likes : [{type: ObjectId , ref: 'User'}],
likeCount: {type: Number, default:0}
})
var UserSchema = new Schema({
})
When a user likes a comment. The user should be added to likes list and
the embedded Comment Subdocument in Blog Document should be updated. I am
not sure how to achieve this.
Help appreciated.