Как мне установить один фрагмент посередине другого?

Это фрагмент, который нужно поставить посередине экрана.

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/addPersonWindow"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <TextView
        android:layout_width="match_parent"
        android:id="@+id/nameText"
        android:layout_height="wrap_content"
        android:text="@string/name"
        app:layout_constraintStart_toStartOf="parent"
        tools:ignore="MissingConstraints" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/addName"
        app:layout_constraintTop_toBottomOf="@id/nameText"
        app:layout_constraintStart_toStartOf="parent"
        tools:ignore="MissingConstraints" />

    <TextView
        android:id="@+id/ageText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:text="@string/age"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/addName"
        tools:ignore="MissingConstraints" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/addAge"
        app:layout_constraintTop_toBottomOf="@id/ageText"
        app:layout_constraintStart_toStartOf="parent"
        tools:ignore="MissingConstraints" />

    <TextView
        android:layout_width="match_parent"
        android:id="@+id/genderText"
        android:layout_height="wrap_content"
        android:text="@string/gender"
        android:layout_marginTop="8dp"
        app:layout_constraintStart_toStartOf="@id/ButtonFemale"
        app:layout_constraintTop_toBottomOf="@id/addName"
        tools:ignore="MissingConstraints" />

    <Button
        android:id="@+id/ButtonFemale"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/female"
        android:layout_marginTop="8dp"
        android:textColor="@color/white"
        android:theme="@style/Button.Green"
        app:layout_constraintTop_toTopOf="@id/addAge"
        app:layout_constraintBottom_toBottomOf="@id/addAge"
        app:layout_constraintEnd_toStartOf="@id/ButtonMale"
        tools:ignore="MissingConstraints" />

    <Button
        android:id="@+id/ButtonMale"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/male"
        android:layout_marginTop="8dp"
        android:textColor="@color/white"
        android:theme="@style/Button.Green"
        app:layout_constraintTop_toTopOf="@id/addAge"
        app:layout_constraintBottom_toBottomOf="@id/addAge"
        app:layout_constraintEnd_toEndOf="@id/ButtonAdd"
        tools:ignore="MissingConstraints" />

    <Button
        android:id="@+id/ButtonAdd"
        android:layout_width="296dp"
        android:layout_height="wrap_content"
        android:text="@string/Add"
        android:layout_marginTop="8dp"
        android:textColor="@color/white"
        android:theme="@style/Button.Green"
        app:layout_constraintTop_toBottomOf="@id/addAge"
        tools:ignore="MissingConstraints" />

</android.support.constraint.ConstraintLayout>

Это тот экран, который открыт, где и нужно поставить верхний фрагмент.

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:padding="8dp"
    android:id="@+id/add_person">

        <ImageView
            android:id="@+id/icon"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="8dp"
            android:layout_marginTop="8dp"
            android:src="@mipmap/ic_launcher_round"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <ImageButton
            android:id="@+id/more"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginEnd="8dp"
            android:layout_marginTop="8dp"
            android:src="@drawable/ic_more"
            android:background="@android:color/transparent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <android.support.constraint.Barrier
            android:id="@+id/barrier_1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:barrierDirection="bottom"
            app:constraint_referenced_ids="icon, more"
            />

        <include
            android:id="@+id/windowOfAdding"
            layout="@layout/fragment_add_person_window"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            />

        <android.support.constraint.Barrier
            android:id="@+id/barrier_2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:barrierDirection="top"
            app:constraint_referenced_ids="next, nextArrow"
            />


        <ImageButton
            android:id="@+id/next"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_circle"
            android:background="@android:color/transparent"
            android:layout_marginBottom="8dp"
            android:layout_marginEnd="8dp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            />

        <ImageButton
            android:id="@+id/nextArrow"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_arrow_right"
            android:background="@android:color/transparent"
            android:layout_marginBottom="8dp"
            android:layout_marginEnd="8dp"
            app:layout_constraintEnd_toEndOf="@id/next"
            app:layout_constraintBottom_toBottomOf="@id/next"
            app:layout_constraintStart_toStartOf="@id/next"
            app:layout_constraintTop_toTopOf="@id/next"
            />


</android.support.constraint.ConstraintLayout>

Фрагмент вставляется, но не хочет вставать посередине экрана. Как решить проблему?

Пробовал include и RelativeLayout