There are plusses and minuses to both approaches. If you include one of the wall elements in the section, i.e. the bottom of the wall, then the enitre curb section will be included in the wall object, since you cannot create associations to any of the individual elements of section elements. That is another deficiency in the product that will hopefully be addressed soon. You would have to change the curb section element from a boundary to a breakline in order for it to be used in the wall object. Otherwise you will have gaps in the wall TIN. Also, if you are intending to use quantity depths for earthwork, the wall quantity will include the curb section elements and vice versa. If you can live with that then including the wall element in the curb section should work fine. That portion of the wall will then maintain a dynamic relationship to the section elements, both horizontally and vertically.
If you do not want the wall to include the curb elements, your next option would be to drape an element over the curb and use it as a boundary for the wall. There are a few problems with this approach however. First off, if any part of the draped element does not completety overlap the curb TIN, Modeler will not be able to update the element and you will receive an error every time the model updates. This can happen if the curb element has to be moved horizontally, so any edits to the curb alignment will require managing the draped elements as well since they are not dynamic to the alignment. You have to be especially careful with draped elements on curves. The reason being that on curves the TIN becomes a series of short chord segments and if the drape element follows the cuve too closely, parts of it will lie over a gap in the chords. Thus any draped element needs to be offset from the back of curb slightly to prevent this. That offset can create other issues in cases where you need to dape elements for more than one object on the curb, especially where curves meet tangents.
Another problem with draping is the software does not always update the draped elements reliably. This is due to a defect in Modeler. Thus you will have to pay close attention to the model to be sure the elements are updating. If you do encounter this problem the only way to get the elements to update is to move them slightly. Needless to say, dealing with this problem can be time consuming and if you are not careful you could end up releasing a bad model.
So, no matter which method you use you will have to deal with issues. So far I have not found either approach to be entirely effective. It's come down to choosing your poison.
Neil Wilson (aka Neilw)
Power Civil v8i 08.11.07.245
AutoCAD Civil 3D 2013