Ok, this isn’t possible unless the pattern was created in Seamly & you still have the pattern & measurement file.
This is possible, you can open the PDF is a vector program and save the pages as JPG’s. Then you can load the JPG’s as images into Seamly, line them up nicely and “copy” the pattern, using actual measurements, to make your modifications.
Sorry, my query wasn’t framed very well.
The pattern(s) that I have are actually downloaded multi-page PDF docs. I wiil try importing these and doing as you suggest.
Thanks for the pointers.