Sluicing and wide scope

Sluices on indefinites or disjunctions may seem to require wide scope for those – but then again, there is a confound…

The following examples may seem slightly odd:

  1. We have to find someone who knows Arabic but we haven't been told who yet.
  2. Somebody always complains about the sound quality. You'll know who soon enough.
  3. You may have a beer or a glass of wine with the evening meal. I don't remember which though.

How is that?

Now the following example may seem to break ranks with (1)–(3) in allowing two readings:

  1. Everybody ordered a starter, but the waitress forgot what.

Do you agree? How could the "new" reading be characterized? (Keyword: 'pair-list')