They had no other choice but to sedate them then feed them the blood. In that case, they will both be sired to the vampire; they will become a part of the family and instinctively be loyal to it. They waited for them to wake up.
Once they had woken up, the couple had not felt this alive in ages. They felt home. The vampire decided to introduce them to their new family.
it was a full moon, meaning they could also celebrate their now werewolf roots. Both Darcy and Eliza could not imagine a better future as a family