I think perhaps you or Peter should be owner, Helene. I don’t think it is possible to pass ownership over to you from me.
However, if you were to create a new map – My places > Maps > Create – you can then import the details from the map I have created by pressing the ‘Import’ button and entering the URL of my map – http://maps.google.com/maps/ms?msid=203176248104282074125.0004b71d5b1ea074f7a6a&msa=0
I would then delete the old one
PS, am going out for a little while now, will check back later if any problems!