How to refer to existing web page from side project?

See more:

.NET

.NET4

Hello All,

I have a relatively big web-site and willing to have a small project to debug one or two pages.
Requirements for small project are:
- project location are different from web-site
- do NOT copy existing code into project folder
- allow using a form designer and other toolsets as usual

Problem :
- Web-site contain only *.aspx & *.aspx.cs (*.aspx.vb) files.
- *.design.cs (*.design.vb) didn’t exist on web-site.
- Without *.design file Studio (2010 & 2015) didn’t allow to use Form Designer in small project.

Question:
- How do I Link an existing *.aspx & *.aspx.cs into the small project, Edit and Save them.

Partial solution was created as following:
- *.aspx & *.aspx.cs added into small project as a Link’s.
- *.aspx & *.aspx.cs bounded using DependUpon
- *.design.cs creted and added to both Big and small projects
This allows completing Link, Edition and Save, but require two files in different places.

part of original (big) project:

<ItemGroup>
  <Content Include="Reports\WebForm1.aspx" />
  <!-- I want to work with WebForm2.aspx in separate project -->
  <Content Include="Reports\WebForm2.aspx" />
  <Content Include="Reports\WebForm3.aspx" />
</ItemGroup>
<ItemGroup>
  <Compile Include="Reports\WebForm1.aspx.cs">
    <DependentUpon>WebForm1.aspx</DependentUpon>
    <SubType>ASPXCodeBehind</SubType>
  </Compile>
  <Compile Include="Reports\WebForm2.aspx.cs">
    <DependentUpon>WebForm2.aspx</DependentUpon>
    <SubType>ASPXCodeBehind</SubType>
  </Compile>
  <Compile Include="Reports\WebForm3.aspx.cs">
    <DependentUpon>WebForm3.aspx</DependentUpon>
    <SubType>ASPXCodeBehind</SubType>
  </Compile>
</ItemGroup>
<!-- file created in the project folder and added into project-->
<ItemGroup>
  <Compile Include="Reports\WebForm2.aspx.designer.cs">
    <DependentUpon>WebForm2.aspx</DependentUpon>
  </Compile>
</ItemGroup>

part of small project with linked pages :

<ItemGroup>
  <Content Include="..\BigSite\Reports\WebForm2.aspx">
    <Link>Reports\WebForm2.aspx</Link>
  </Content>
</ItemGroup>
<ItemGroup>
  <Compile Include="..\BigSite\Reports\WebForm2.aspx.cs">
    <Link>Reports\WebForm2.aspx.cs</Link>
    <DependentUpon>WebForm2.aspx</DependentUpon>
    <SubType>ASPXCodeBehind</SubType>
  </Compile>
  <!-- file copied into local folder and added into project -->
  <Compile Include="Reports\WebForm2.aspx.designer.cs">
    <DependentUpon>WebForm2.aspx</DependentUpon>
    <SubType>ASPXCodeBehind</SubType>
  </Compile>
</ItemGroup>

Is there an option to avoid adding a *.design.cs file? Something what Studio used when edit pages without *.design.cs on existing web-site?