Stringer was not originally designed with this process in mind. However a workaround can be used to merge your old surface with a newly created one.
Follow the below steps to achieve this:
- Import the new points into the drawing
- Run 'Join All Codes' to create the surface for the new points
- Right Click a Triangle from the previous job and choose 'Select Similar'
- Type 'Region' into the command line and press enter
- Right-click on a triangle again and choose 'Select Similar'
- Type 'Explode' into the command line and press enter to form breaklines
- Open the 'Surface Manager' and select 'Breaklines'
- Use the drop-down to select the layer the newly formed breaklines are on and select 'Add'
- Select the Build Surface command
