EntitySet<T> in LINQ to SQL- using it and removing it

I've got a pair of tables in my database. One of which has a primary key (a simple numerical ID), the other has that ID as a foreign key.

The first table has suddenly gained an EntitySet<OtherTable>. If I add a new OtherTable() to this, is it automatically sent to the database, and the ID's linked up, etc, when I use SubmitChanges()?

Secondly, the relationship isn't many-to-one, it's one-to-one, a corresponding entry in the second table is optional and singular. As开发者_如何学Python such, a container like EntitySet isn't really appropriate for this relationship. An OtherTable? would be a more appropriate representation. How can I inform LINQ to SQL of this?

Set Unique = true in the associaton properties. That should adjust it to being 1:1