Primary Key In A Partial View Shared By Create And Edit Views

I have a partial view (user control) that is shared by my Create and Edit views. When I use it in the Edit view, I have to to include an hidden field (Html.HiddenFor) to prevent a 'Row changed or not found' error in my data service, but when I use it in the Create view, I have to remove the PK hidden field, to prevent an error over trying to insert into an identity column. It is not feasible to not use identity columns in this application, so how can I 'switch' that PK hidden field on or off depending on which action has been invoked?

Post Action Code:

[HttpPost]
public ActionResult Edit(JobCardViewData viewData)
{
try
{
jobCardService.Update(viewData.JobCard);
Edit View Excerpt:
<% Html.RenderPartial("JobCardInput", Model); %>
Partial Excerpt:
<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<Poynting.Installation.Web.ViewData.JobCardViewData>" %>
<% using (Html.BeginForm())