How to use multiple custom Mongoose Schemas as sub-schemas for the type field instead of Schema.Types.Mixed?

I'm working with Mongoose to create a StepperDataSchema that contains a celebratorDetails field. This field can have one of two possible sub-schema structures:

1.BirthdayCelebratorDetailsSchema

2.WeddingCelebratorDetailsSchema

Here are the definitions of my schemas:

// First Custom Schema
const BirthdayCelebratorDetailsSchema = new Schema({
  name: { type: String, required: true },
  celebratorType: {
    type: String,
    enum: Object.values(CelebratorTypes),
    required: true,
  },
  age: {
    type: Number,
    required: true,
    min: 1,
    max: 120,
  },
});

// Second Custom Schema
const WeddingCelebratorDetailsSchema = new Schema({
  firstCelebrator: {
    name: { type: String, required: true },
    type: {
      type: String,
      enum: Object.values(WeddingCelebratorTypes),
      required: true,
    },
    parentsNames: { type: String, required: true },
  },
  secondCelebrator: {
    name: { type: String, required: true },
    type: {
      type: String,
      enum: Object.values(WeddingCelebratorTypes),
      required: true,
    },
    parentsNames: { type: String, required: true },
  },
});

Currently, in my StepperDataSchema, I'm using Schema.Types.Mixed to represent celebratorDetails:

const StepperDataSchema = new Schema({
  celebratorDetails: {
    type: Schema.Types.Mixed, // ❌ I want to use the custom schemas here
    required: true,
  },
  // other fields...
});

I want to strictly type celebratorDetails to only allow either BirthdayCelebratorDetailsSchema or WeddingCelebratorDetailsSchema, instead of the generic Schema.Types.Mixed

Any guidance or examples on how to achieve this would be greatly appreciated!