Adding a new Relationship Type

Question

Since a relationship between a Service Request and the user who completed it doesn't exist and there is an obvious need for it, I want to add it in manually.  I ask the community to review the following MP XML. 
Please, let me know if I am missing anything.
Also, is there an Engineering Blog which can direct me on how to add a new workflow which will add this relationship to Service Requests upon completion?
<ManagementPack ContentReadable="true" SchemaVersion="2.0" OriginalSchemaVersion="1.1" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<Manifest>
<Identity>
<ID>WorkItem.Relationship.Extension</ID>
<Version>1.0.0.0</Version>
</Identity>
<Name>WorkItem.Relationship.Extension</Name>
<References>
<!-- System Library -->
<Reference Alias="System">
<ID>System.Library</ID>
<Version>7.5.8501.0</Version>
<PublicKeyToken>31bf3856ad364e35</PublicKeyToken>
</Reference>
<!-- System Work Item Library -->
<Reference Alias="WorkItem">
<ID>System.WorkItem.Library</ID>
<Version>7.5.2905.0</Version>
<PublicKeyToken>31bf3856ad364e35</PublicKeyToken>
</Reference>
<!-- Service Request Librarys -->
<Reference Alias="ServiceRequest">
<ID>ServiceManager.ServiceRequest.Library</ID>
<Version>7.5.2905.0</Version>
<PublicKeyToken>31bf3856ad364e35</PublicKeyToken>
</Reference>
<Reference Alias="CoreService">
<ID>System.WorkItem.ServiceRequest.Library</ID>
<Version>7.5.2905.0</Version>
<PublicKeyToken>31bf3856ad364e35</PublicKeyToken>
</Reference>
</References>
</Manifest>
<TypeDefinitions>
<EntityTypes>
<RelationshipTypes>
<RelationshipType ID="Extension.WorkItemCompletedByUser" Base="System!System.Reference" Accessibility="Public" Abstract="true">
<Source ID="WorkItemCompletedByUser" MinCardinality="0" MaxCardinality="2147483647" Type="WorkItem!System.WorkItem" />
<Target ID="CompletedByUser" MinCardinality="0" MaxCardinality="1" Type="System!System.User" />
</RelationshipType>
</RelationshipTypes>
<TypeProjections>
<TypeProjection ID="System.WorkItem.ServiceRequestProjection" Accessibility="Public" Type="CoreService!System.WorkItem.ServiceRequest">
<Component Alias="CompletedBy" Path="$Target/Path[Relationship='Extension.WorkItemCompletedByUser']$" />
</TypeProjection>
</TypeProjections>
</EntityTypes>
</TypeDefinitions>
<LanguagePacks>
<LanguagePack ID="ENU" IsDefault="true">
<DisplayStrings>
<DisplayString ElementID="WorkItem.Relationship.Extension">
<Name>WorkItem.Relationship.Extension</Name>
</DisplayString>
<DisplayString ElementID="Extension.WorkItemCompletedByUser">
<Name>Completed By User</Name>
<Description>Relationship between a work item and the user that completed it</Description>
</DisplayString>
</DisplayStrings>
</LanguagePack>
</LanguagePacks>
</ManagementPack>

Answer 1

I'm not sure the need is as obvious as you suspect.
The first problem I come to is "which user?". If the Service Request has 10 activities steps, from 10 different users, which of them is the Service Request Completed user? The only way this would be informative would be the rare service requests that have
no processes and must be handled manually, in which case the real fix is to create processes for these service requests so they don't need to be handled manually.
As to setting this: there's two big options:
the way this is set for Incidents is by the form controls. If you were to replicate that behavior, you'll probably want to add a custom control to the form that sets the completed user to the current console if the status has changed to completed during
that session, which is a lot of real SDK development work.
Alternatively, you could use a workflow that triggered on the status being changed from anything else to completed, and set this value based on the last user to edit this SR. I'd recommend doing this with a
custom workflow in PowerShell, but you could use Orchestrator, C# workflows, patrol scripts, etc.