One of the key features of the WiX toolset is the ability to distribute setup to across developers. The following is a common pattern where a central team maintains the definition of the setup package and other teams contribute the bulk of the content.

Central team:

<Wix>
  <Product ...>
    <MajorUpgrade ... />

    <Feature Id='Main'>
      <ComponentGroupRef Id='TeamA' />

      <Feature Id='SubFeature'>
        <ComponentGroupRef Id='TeamB' />
      </Feature>
    </Feature>
  </Product>
</Wix>

Team A:

<Fragment>
  <ComponentGroup Id='TeamAFoo' Directory='FooFolder'>
    <Component>
      <File Source='path\to\teama\foo.dll' />
    </Component>
    <Component>
      <File Source='path\to\teama\foo.dat' />
    </Component>
  </ComponentGroup>
</Fragment>

<Fragment>
  <ComponentGroup Id='TeamABar' Directory='BarFolder'>
    <Component>
      <File Source='path\to\teama\bar.dll' />
    </Component>
    <Component>
      <File Source='path\to\teama\bar.txt' />
    </Component>
  </ComponentGroup>
</Fragment>

Team B: