Custom ViewGroup with children inserted at specific spot

Question

I have several Activities in my Android app that have the same basic structure, and I'm trying to make my layouts DRY. The duplicated code looks like the below. It contains a scrollable area with a footer that has "Back" and "Dashboard" links. There's also a FrameLayout being used to apply a gradient on top of the scrollable area.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:custom="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">
        <ScrollView
            android:layout_width="match_parent"
            android:layout_height="689px">
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical">

                <!-- THE REAL PAGE CONTENT GOES HERE -->

            </LinearLayout>
        </ScrollView>
        <ImageView
            android:src="@drawable/GradientBar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom" />
    </FrameLayout>
    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="50px"
        android:background="?attr/primaryAccentColor">
        <Button
          android:layout_width="wrap_content"
          android:layout_height="26px"
          android:layout_gravity="center_vertical"
          local:MvxBind="Click GoBackCommand" />
        <Button
          android:layout_width="wrap_content"
          android:layout_height="26px"
          local:MvxBind="Click ShowDashboardHomeCommand" />
    </FrameLayout>
</LinearLayout>

To de-dupcliate my Activities, I think what I need to do is create a custom ViewGroup inherited from a LinearLayout. In that code, load the above content from an XML file. Where I am lost is how to get the child content in the Activity to load into the correct spot. E.g. let's say my Activity now contains:

<com.myapp.ScrollableVerticalLayoutWithDashboard
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!-- THE REAL PAGE CONTENT GOES HERE -->
    <TextView android:text"blah blah blah" />

</com.myapp.ScrollableVerticalLayoutWithDashboard>

Now how do I cause the "blah blah blah" to appear in the correct place? I'm pretty sure if I did this, I would either end up with "blah blah blah" at the top or bottom of the page, not in the middle of the ScrollView as desired.

I'm using API 21 / v5.0+. Technically I'm doing all this with Xamarin, but hopefully that's irrelevant to the answer?

EDIT: An example of what the result would look like is this. The footer and gradient are part of the custom ViewGroup, but the rest would be content within the custom ViewGroup.