I know they are marmite names and you may well hate them both, but it's definitely got to be one or the other :)
(Apologies to anyone who knows me IRL and has had this endless debate with me, too - I just need to get a wider opinion)
So which should it be:
Ottilie - to be known as Ottie - or Mabel?
Surname is a pretty common English one that goes with most names