Updating an entity object with relation to another table-object (NxN) (Inserting, deleting)

I did, however, locate it. I'm putting it out there in the hopes that it may, at the at least, inspire others to do the same:

Note: In order to handle the operation in one step, we must utilise transactions.

To be inserted

As per normal, I create an object in Table 1 and, for property 4, I create a list of objects in Table 2 (attaching first), after which I assign the list to attribute 4.

(using context = new Dbcontext())
{
  using (var transaction = context.Database.BeginTransaction(IsolationLevel.Serializable))
  {
    Table1 object1 = new Table1
    {
      Attribute1 = 1, //(autoincrement really)
      Attribute2 = "random value",
      Attribute3 = "random value",
    };

    foreach (Table2 obj2 in NewValues)
    {
      Table2 o = new Table2() {Attribute1 = obj2.int, Attribute2 = obj2.string};
      context.Table2.Attach(o);
      object1.Attribute4.Add(o);
    }
  }
}

As an update

I just delete in order to insert afterwards.

Another technique for inserting:

Keep List in a temporary List. adding Object1 to the context without Attribute4. Add temp List to object1 to complete. Attribute4.

(using context = new Dbcontext())
{
  using (var transaction = context.Database.BeginTransaction(IsolationLevel.Serializable))
  {
    Table1 object1 = new Table1
    {
      Attribute1 = 1, //(autoincrement really)
      Attribute2 = "random value",
      Attribute3 = "random value",
    };

    List<Table2> tempTable2 = new List<Object2>();
    foreach (Table2 obj2 in NewValues)
    {
      Table2 o = new Table2() {Attribute1 = obj2.int, Attribute2 = obj2.string};
      tempTable2.Add(o);
    }

    context.Table1.Add(object1);
    context.SavesChanges();

    Table1 object11 = context.Table1.First(o => o.Attribute1 == object1.Attribute1);
    object11.Attribute4 = tempTable2
    context.SavesChanges();
  }
}