In my opinion, if he took Genette, she may be near where Caroline, Sarah and Susan were found; the Midlands Triangle.
I think Black took several girls across Europe, as is suggested, but there are some I DON'T think he took.
April Fabb, 13, Norfolk, 1969. I DON'T think he took April. While it is said he visited Norfolk, Peter Tobin is far more likely to have been there ON THE DAY. April looks her age, unlike Genette. I don't think Black would have tried to abduct Theresa Thornhill, as I said above, if he knew she was fifteen.
Suzanne Lawrence, 14, Essex, 1979. Again, someone who looked her age. I heard it mentioned somewhere that Black knew about the crime, despite the fact it was not publicized much, but as a truck driver, it's extremely likely that he may have brought a local paper frequently. Especially if that route going back was a favorite for him.
However, there are a few besides Genette that I think he took.
Bernadette Connolly, 10, County Sligo, 1970.
http://www.independent.ie/irish-new...opening-of-connolly-murder-case-26588858.html
Bernadette, like Genette, was riding a bicycle when she was abducted. Four months after her abduction, she was found dead. Her case bears similarities to Genette's abduction and Jennifer Cardy's abduction.
Ramona Herling, 11, Germany, 1989.
http://www.doenetwork.org/cases-int/416dfdeu.html
Last seen going to a swimming pool. Black had been a lifeguard and had a thing about swimming pools. Missing.
Cheryl Morrien, 7, Netherlands, 1986
http://www.doenetwork.org/cases-int/422dfnet.html
I'd seen this mentioned a few times before; apparently the filthy man went to the Netherlands for photos. People like Black make me sick! Cheryl lived near the Amsterdam dock area.