Unfortunately, with Web-based applications you do not have the luxury of using specialized controls, such as grid objects, but rather you are limited to what you can do with HTML and DHTML.  Certain sites utilize Java and ActiveX controls, but I recommend that you stay away from these, because you will most probably run into compatibility and/or performance issues.

To accommodate the limitations of the medium, most Web application developers simplify the user interface of their applications and limit the number of functions in a single page.  For example, in your particular example, you could have a table or list box containing all child rows, but force the user to click on a link or button and present a secondary page that allows the editing of a single child record at a time.

You can actually be pretty fancy with DHTML and create a pretty functional DHTML-based grid, but you will have to make sure that you write your code so that it is compatible with the browsers that your target user-base is using.  There are several useful Web sites and books that you can use to learn how to write effective DHTML code.  A good place to start is the Useful Links page in our documentation.