I know what you mean now
You want to do something like this:
Goal
Fetch one _Customer _and its related _Orders _(prefetch), ordered by Order.Employee.FirstName, additionally fetch each associated employee of each order.
PreidicateExpression code
IPrefetchPath2 path = new PrefetchPath2((int)EntityType.CustomerEntity);
path.Add(CustomerEntity.PrefetchPathOrders, 0, null,
new RelationCollection(OrderEntity.Relations.EmployeeEntityUsingEmployeeId),
new SortExpression(EmployeeFields.FirstName | SortOperator.Ascending))
.SubPath.Add(OrderEntity.PrefetchPathEmployee);
PathEdges code
I didn't find a way for doing this with PathEdges (will look into it).
Lambda expressions code (using OrderBy method)
var q = (from c in metaData.Customer
where c.CustomerId == "ALFKI"
select c)
.WithPath<CustomerEntity>(
p => p.Prefetch<OrderEntity>(c => c.Orders)
.OrderBy(o => o.Employee.FirstName)
.SubPath( p2 => p2.Prefetch<EmployeeEntity>(o => o.Employee)));