Lorcan and Bell didn't waste time and eventually went on a three hours drive to the place where Mrs. Miller said Silas's cousin is.
But before that, Lorcan made sure that Lydia has Brylee's company since it is obvious that he would be going home late. That morning, he sent Lydia to Miliani and told Brylee to accompany her the rest of the day while he was gone. He would be at ease if he leaves Lydia with at least one of his nieces.
If it was before and he didn't know about his niece's abilities, he wouldn't leave Lydia with them and would probably take her to Rowan's house to keep her safe.
But things are different now. At least one of his nieces is probably comparable to a battalion of soldiers. Enough to protect the love of his life and his twins.