TeamCity - CI w/ Multi-project .NET solution using SOA build and delivery issues
So you need to create packages for each of the three sites so that you can deploy each one individually.

The first step is to create a .nuspec file for each of the IIS websites you want to package:


Install OctoPack and read the entire article
Create three empty text files next to the .csproj, give it the same base filename as the .csproj, thus if it is MyApp.API.csproj you want to create an empty text file called MyApp.API.nuspec.
In each of these .nuspec files paste in the following template:

&lt;?xml version="1.0"?&gt;
&lt;package xmlns="http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd"&gt;
&lt;metadata&gt;
    &lt;id&gt;Sample.Web&lt;/id&gt;
    &lt;title&gt;Your Web Application&lt;/title&gt;
    &lt;version&gt;1.0.0&lt;/version&gt;
    &lt;authors&gt;Your name&lt;/authors&gt;
    &lt;owners&gt;Your name&lt;/owners&gt;
    &lt;licenseUrl&gt;http://yourcompany.com&lt;/licenseUrl&gt;
    &lt;projectUrl&gt;http://yourcompany.com&lt;/projectUrl&gt;
    &lt;requireLicenseAcceptance&gt;false&lt;/requireLicenseAcceptance&gt;
    &lt;description&gt;A sample project&lt;/description&gt;
    &lt;releaseNotes&gt;This release contains the following changes...&lt;/releaseNotes&gt;
&lt;/metadata&gt;
&lt;/package&gt;

Customize the template for each of your projects.
Update TeamCity to add /p:RunOctoPack=true to the msbuild command line
Publish your packages with the following msbuild arguments:


/p:OctoPackPublishPackageToHttp=http://your.octopusserver.com/nuget/packages
/p:OctoPackPublishApiKey=API-ABCDEFGMYAPIKEY



You may have to play around a bit, but essentially the above is taken from this article so treat that as your bible.