//These middle aged men were in their teens/ early 20s when the offences took place. They may have look different then, than they do now. The girls considered them as their boyfriends before the exploitation started, so there must have been a level of attraction.//
Not impossible, but unlikely that any of the girls considered these particular four as their "boyfriends".
The initial grooming is usually done by a good looking young guy (the "Dangerous Lover Boy") with a flash car and loads of money to chat the girls, who, when he's got her to fall for him , will "introduce" her to his cousins, his uncle and his mates. At this stage she will probably be drinking heavily.