I'm actually descended from Benedict's father, so not really related to Martina at all - just got sucked in by the mystery! Not sure I can add anything about Murcia or Felicitas, but they're all on my Ross Family Tree in Ancestry (open for members to view) and I have a go at them from time to time.
I'm not convinced that Martina junior is a Shave, but have put her in twice just in case (once with Benedict & Martina as parents, and again with Harriet & Walter).
I was wondering about the witnesses too!