Mongoose collection design - node.js

Question

This is probably going to get downvoted off of here but Im having a hard time wrapping my head around this issue.
In my Mongoose Schema I have a list of groups. These groups will be people, they will have an _id of that person, or if they dont have an _id they be listed by their email.
It makes sense to me to use groups so I can loop through a list without having to hardcode the list names, reason being is that I would like to let users add thier own groups. What I am not understanding is....
1) How can I allow the users to add to this collection, can I just do groups.push(groupName)? Wont Mongoose kick it back out? Also how does it know that I want Ids, name, email in the other field of collection.
2) I need to display the names of the groups, then separately the individuals in the group. I dont think I can show the keys in this fashion. So how can I display the names of the groups.
I think Im doing this fundamentally wrong but I cant figure out the right way
const mongoose = require("mongoose"),
bcrypt = require('bcrypt-nodejs');
const passportLocalMongoose = require("passport-local-mongoose");
mongoose.createConnection("mongodb://localhost/familySite");
const userSchema = new mongoose.Schema({
username: {type:String, required: true, unique: true},
email: {type: String, required: false, unique: false},
password: { type: String, required: true},
resetPasswordToken: String,
resetPasswordExpires: Date,
profile: {picture: String, nickname: String},
permission:{app: Number}, //This will tell the app what level, 0 for Admin, 1 for User
name: {
first:String,
middle:String,
last:String,
other: {
startDate: Date,
endDate: Date,
first: String,
middle: String,
last: String
}
},
lastName: String,
address: String,
city: String,
state: String,
zipCode: Number,
phone: Number,
birthday: Date,
birthplace: String,
userCover: String,
categories: Array,
defaultPermission: Number,
events: [{
type: mongoose.Schema.Types.ObjectId,
ref: "Event"
}],
moments: [{
type: mongoose.Schema.Types.ObjectId,
ref: "Moments"
}],
instants: [{
type: mongoose.Schema.Types.ObjectId,
ref: "Instant"
}],
groups:
[{family:{
type: mongoose.Schema.Types.ObjectId,
ref: "User"},
groupName: String,
name: String,
email: String
},
{friends:{
type: mongoose.Schema.Types.ObjectId,
ref: "User"},
name: String,
email: String,
groupName: String,
},
{colleagues:{
type: mongoose.Schema.Types.ObjectId,
ref: "User",
name: String,
email: String,
groupName: String,
}
}],
likedMoments: [{ //This is for what this person likes, so they can refer later
type: mongoose.Schema.Types.ObjectId,
ref: "Moments"
}],
likedEvents: [{ //This is for what this person likes, so they can refer later
type: mongoose.Schema.Types.ObjectId,
ref: "Event"
}],
favoriteEvents: [{ //This is for personal events that are favorited
type: mongoose.Schema.Types.ObjectId,
ref: "Event"
}],
favoriteMoments: [{ //This is for personal moments that are favorited
type: mongoose.Schema.Types.ObjectId,
ref: "Moments"
}]
})
// I THINK I NEED TO MAKE THIS A METHOD SO I CAN GET IT ALL INTO APP.JS
// This uses bcrypt to hash passwords
userSchema.pre('save', function (next){
var user = this;
var SALT_FACTOR = 5;
if(!user.isModified('password')) return next();
bcrypt.genSalt(SALT_FACTOR, function (err, salt) {
if (err) return next(err);
bcrypt.hash(user.password, salt,null, function (err, hash){
if(err) return next(err);
user.password - hash;
next();
});
});
});
userSchema.methods.comparePassword = function(candidatePassword, cb) {
bcrypt.compare(candidatePassword, this.password, function(err, isMatch) {
if (err) return cb(err);
cb(null, isMatch);
});
};
userSchema.plugin(passportLocalMongoose);
module.exports = mongoose.model("User", userSchema)