How can I control the element names of serialized subclasses?

Let's say I have the following class structu开发者_运维百科re (simplified from my real-world problem):

Public Class PC_People_Container
    Private _people_list As New List(Of PL_Person)

    Public Sub New()
    End Sub

    Public Sub Add(ByVal item As PL_Person)
        _people_list.Add(item)
    End Sub

    Public Property PeopleList As List(Of PL_Person)
        Get
            Return _people_list
        End Get
        Set(ByVal value As List(Of PL_Person))
            _people_list = value
        End Set
    End Property

End Class

Public Class PL_Person
    Private _Name As String
    Public Property Name As String
        Get
            Return _Name
        End Get
        Set(ByVal value As String)
            _Name = value
        End Set
    End Property

    Private _Contacts As ContactObject
    Public Property Contacts As ContactObject
        Get
            Return _Contacts
        End Get
        Set(ByVal value As ContactObject)
            _Contacts = value
        End Set
    End Property

    Public Sub New()
    End Sub

End Class

Public Class ContactObject
    Public Property PhoneNumber As String
    Public Property EmailAddress As String

    Public Sub New()
    End Sub
End Class

If I were to serialize this, I'd get the default assigned node names in my XML. That means my root is named PC_People_Container and each person in the list is marked up as PL_Person. I know I can change the root node using <XmlRoot(ElementName:="PeopleContainer")>. The trouble is doing that for the subclasses. I can't use the <XmlRoot> tag on PL_Person class because there can't be two root elements, and IntelliSense throws a fit when I try to use the <XmlElement> tag on a class like I would on a property. Is it even possible to control what those subclasses are named when they're serialized as child nodes?

PL_Person and ContactObject are not subclasses as you call them, they are merely property types.
This makes your question confusing because it suggests you may have a problem with inheritance (subclasses are classes that inherit from some base class) when in fact you just want your property elements to be named differently.

You should decorate your properties (not classes) with <XmlElement> to specify custom name:

<XmlElement("Persons", GetType(PL_Person))>
Public Property PeopleList As List(Of PL_Person)

As an afterthought, I would definitely not recommend calling your classes using such an awkward convention. In .NET, you should not use any prefixes or underscores in class names. Just call it Person.