Creating Two Foreign key mongoose inside a controller

Question

Hi I want to implement this snippet of my class diagram using mongoose.

Here is my logic model in detail:

Here is the definition of my Mother model:

const mongoose = require('mongoose')

const motherSchema = mongoose.Schema({
    cniMother: { type: Number, required: true },
    name: { type: String, required: true },
    surname: { type: String, required: true },
    birthDay: { type: Date, required: true },
    birthPlace: { type: String, required: true },
    address: { type: String, required: true },
    phone: { type: Number, required: true },
    occupation: { type: String, required: true },
}); 

module.exports = mongoose.model('Mother', motherSchema);

Here is the definition of my Declared model:

const mongoose = require('mongoose')

const declaredSchema = mongoose.Schema({
    name: { type: String, required: true },
    surname: { type: String, required: true },
    father: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Father',
        //required: true,
    },
    mother: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Mother',
        //required: true,
    },
    birthDay: { type: Date, required: true },
    birthPlace: { type: String, required: true },
    gender: { type: String, required: true },
    nationality: { type: String, required: true }
}); 

module.exports = mongoose.model('Declared', declaredSchema);

I want to retrieve the name of the father and the mother corresponding to the declared. Can anyone help me please?