Visible crew/equipment: When Michael is closing the windows when the lost boys are going to attack the house, he passes in front of a cabinet and you can see the reflection of a crewmember on the glass.
Visible crew/equipment: A harness is visible when Michael is floating in his room.
Answer: Because the Head vampire, Max, had fallen in love with Michael's mom. At the end of the movie he said, "Boys need a mother and if I could get Michael and Sam into the family, you would have no choice but to join us."