map a custom enum list to a custom form property in an extended incident class in scsm 2012 R2

I'm struggeling to understand how to map a custom enum list to a custom form property in an extended incident class in SCSM 2012 R2 using authoring tool.

Here's what i want to have happen:

I am going to publish a request offering on my SMPortal for allowing users to submit basic IT incidents. I want the form to include "Whom does this problem affect" (answers(This is the custom enum list): Me, Multiple Users, Whole department or Whole company), "What is the problem about", "Description" and "Attachments".

Here's what i've done:

In the authoring tool i created a MP for the custom enum list and put only the list in it. I sealed the MP and imported it.

I created another unsealed MP called TST.Incident.Library for storing incident library customizations and extended the incident class to add an extension class i called ClassExtension_Affected scope with a custom property i called AffectedScope. Then i am trying to set the datatype of this property to "list". In the "select a list" dialog i cannot chose my previously sealed MP with the custom enum list in it. Why?

• Do i need to scratch the sealed MP and put the custom enum list in the latter TST.Incident.Library MP instead?
• If so, can i do that and keep this MP unsealed, or will i get an error on import saying "Unsealed management packs should not contain type definitions"
• Should i create one sealed MP for both the custom enum list and the extension class + custom property?

In the Authoring tool, load the sealed MP created first that contains the custom enum list together with the second unsealed MP. If they are not both loaded at the same time Authoring tool does not know about the custom list in the first MP.