Ok, I found your image
I’m a little uncertain about grading as such, but I understand it to be the resizing of patterns from one size to another size. If this is the case, then this is all done ‘inside the program’ for you. The sizes are handled by the measurements file created in SeamlyME.
When you create a pattern, you load up the measurements file and use the measurements in formulas to create the lines and curves. Once your pattern is created, you can change the size of the pattern simply by loading a different measurement file, or, if you have created a multi-size measurement file, simply by changing the size in the bottom left corner. If your pattern has been created using references to the measurements file everywhere, then your pattern should change size smoothly, including the neckline.
To have multiple sized patterns on one sheet, you will need to export the pattern to svg and lay them out in a graphics program like Inkscape and position them manually.
I hope this answers your question