Shaping points do as their name suggests shape the route, they tell the device to go a certain way. Provided that they have been used sensibly when the route was created they will ensure that the shared route remains as intended. The reason I suggest copying and recalculating the route first is that the shaping points would have been put in to force the route on certain roads by the person creating the route. If the settings are even slightly different or the map version is different there is a risk that the route may not transfer as intended.
Further points can be added at that stage to correct this. Shaping points should be placed just after junctions to force the route to take a chosen road. They are for guidance only and the device should no insist on passing through each one. I prefer Mapsource where they are called via points and are, by default, not announced by the device. In Mapsource such via point are, by default, unannounced, I believe that you have to tell Basecamp which ones you want unannounced. Mapsource also shows up thos via points that have been place off the route by showing them as a green dot. This makes spotting those points placed on the wrong side of a dual carriageway easy to spot. If you are using Basecamp I am sure someone else will come along and put you right-for me life is too short and too busy to bother with Basecamp although i know it has its admirers
If I have a particular destination I really want to get to ( maybe a pre booked hotel) I make that a waypoint rather than a via point. That way it goes into "favorites" when I download the route so if plans change I can easily find it and get the device to take me there. Maybe its just my age but I have been know to delete a route by mistake. Having my destination in favorites at least gets me there if not by my chosen route.
John