How to inherit from two content types

Question

How could i inherit from two contentypes? Doing like this dont work?

   <ContentType ID="0x010100C568DB52D9D0A14D9B2FDCC96666E9F2007948130EC3DB064584E219954237AF390064DEA0F50FC8C147B0B6EA0636C4A7D4" Name="Welcomepage" Group="My Content Types" Description="Welcome page" Inherits="TRUE" Version="0">
<ContentType ID="0x010100C568DB52D9D0A14D9B2FDCC96666E9F2007948130EC3DB064584E219954237AF3900242457EFB8B24247815D688C526CD44D010021935596B4CE427A892D41E2BBED1797" Name="My own content type" Group="My Content Types" Description="Welcome page" Inherits="TRUE" Version="0">

<FieldRefs>
  <FieldRef ID="{e854ecfc-6f7e-47e5-8b86-6f7cac951fca}"  Required="FALSE" Name="PageContent1" />
  <FieldRef ID="{ebc7bfe0-c3fd-4967-8127-8a30f2894d19}"  Required="FALSE" Name="PageContent2" />
  <FieldRef ID="{e3d9a193-a06e-4e61-9f57-67048ac9be0c}"  Required="FALSE" Name="PageContent3" />
</FieldRefs>


 </ContentType>
 </ContentType>

Answer 1

You can only inherit from one parent, so if you want to inherit both ContentTypeA and ContentTypeB into ContentTypeC, you need to inherit ContentTypeB from ContentTypeA and ContentTypeC from ContentTypeB.

Answer 2

Doing this will definitely not work. You are talking about nesting content types, which is not possible in SharePoint. Refer to this MSDN article on Content Type IDs and Inheritance: https://msdn.microsoft.com/en-us/library/aa543822%28v=office.14%29.aspx

Content types are inherited by using the ID of parent content type and adding another ID at the end:

More info on Content Type hierarchy here: https://msdn.microsoft.com/en-us/library/office/ms452896%28v=office.14%29.aspx