MVC3 Routing - Routes that builds on each other

I have an AREA setup in my project. I need to make the routes for the area progressive, meaning that the route will build on each other.

I'm looking at this as something like a link list. Each node in the list will have a reference to a parent. As move from left to right in the list it builds, and from right to left it removes.

In the area, I have companies and that have contacts, and child companies.

For example, I have companies that would have the following:

 /Companies/list
  /Company/{Id}
  /Company/{id}/add
  /Company/{id}/edit
  /Company/{id}/delete

For the contact section I need to create the following routes:

 /Company/{id}/contacts/list
 /Company/{id}/contact/{id}/add
 /Company/{id}/contact/{id}/edit
 /Company/{id}/contact/{id}/delete

How do I make sure that /Company/{id} is always in the Contact and Child Company sections of the route?

I hope that I have made my question clear.

Subjective Generalities (take with a pinch of salt):

First off, you are using Company (singular) for companies, but then you are using contacts (plural) for the contacts. There is nothing wrong with this, from a structural point of view, but your users will thank you if you are consistent with your pluralizations. I would use the plural in both cases, but that is just my preference... it looks more like English.

You also use lower case for contacts, but upper case for Company. Doesn't look professional.

The next thing that is confusing is that you are using two {id} parameters, one for companies, one for contacts. I presume these are the ids for Company and Contacts respectively. But I am confused, but being human, I am able to deduce context unlike a computer. So you would be better of specifying the parameters in your routes. Ie:

/Companies/{CompanyId}/Contacts/{ContactId}/[action]

Answering your Question with an Example:

I get the feel you don't understand routes properly. If you did, your question would be more specific.

Your route parameters can come from a number of sources, depending on how the route is requested.

You could hard code it into a link. Or, more usefully, your route registration would be designed to catch requests that map to your Action signatures.

For example, I have an eLearning app with tutors, pupils, courses and steps (ie, the steps are like sections of a course, the pupil advances through the course step by step)

The route registration looks something like:

Route or Area Registration:

context.MapRoute(
    "StepDisplay",
    "Course/{CourseId}/Step/{StepOrder}/Pupil/{PupilName}/{TutorName}",
    new { controller = "Course", action = "Display", TutorName = UrlParameter.Optional },
new[] { "ES.eLearningFE.Areas.Courses.Controllers" }
);

This route will catch a request from the following ActionLink:

ActionLink in View:

@Html.ActionLink(@StepTitle, MVC.Courses.Course.Actions.Display(Model.CourseId, step.StepOrder, Model.Pupil.UserName, tutorName))

Now, I just need to show you the Display action's signature:

CoursesController:

public virtual ActionResult Display(int CourseId, int StepOrder, string PupilName, string TutorName)

There are a few things to note here:

That I am able to call this specific route by giving the user a link to click on.
I construct this link using the Html.ActionLink helper
I have used David Ebbo's t4mvc nuget package so that I can specify the action I am calling and its parameters. By which I mean specifying the ActionResult parameter of the Html.ActionLink helper using:

MVC.Courses.Course.Actions.Display(Model.CourseId, step.StepOrder, Model.Pupil.UserName, tutorName)

If you think about it, what routes do is translate the url of a request into an action, so the parameters of my route are either the controller name, the action name or else they are the names of parameters in the action signature.