Posting xml to IEM for MAG creation

I am trying to create a multiple action group by posting an xml to IEM using the REST API for action create.
In BES.xsd the MultipleActionGroup element is allowed to contain both MemberAction and SourcedMemberAction elements.
I tried to send a mix of one MemberAction at first and then multiple SourcedMemberAction elements and it worked fine.
When I tried to add one more MemberAction after all the SourcedMemberActions I got an XML parsing error:

  1. {
  2. "format": "Unexpected server error: {message}",
    
  3. "arguments":
    
  4. [
    
  5.     "XML parsing error: element 'MemberAction' is not allowed for content model '(Title?,Relevance?,PreGroupActionScript?,MemberAction*,SourcedMemberAction*,PostGroupActionScript?,Settings?,SettingsLocks?,Domain?,Target?,SourceFixletID?)' Line 197, Character 24"
    
  6. ]
    
  7. }

I don’t understand why they let me add a MemberAction at the beginning but not at the end also. If I add the exact same MemberAction at the beginning (so now I have 2 MemberAction elements) it works fine.