User = new Schema({
firstName: 'String',
lastName: 'String,
otherInfo: [{type: Schema.ObjectId, ref: 'OtherInfoSchema'} ]
});User.find({ ... }).populate('otherInfo');...
lastName: 'String,
otherInfo: [
{_id: '0', name: '', ... },
{_id: '1', name: '', ... }
]