aantroffen… met?
" …waar zij ook Dorine aantroffen, die met haar zwager kennis maakte" .
Zij troffen Dorine aan.
Dorine maakte kennis met haar zwager.
Wat is precies het probleem?
That evening after dinner, Van der Welcke, Constance and Addy went to the home of Mrs. Van Lowe, where they also encountered Dorine, who was getting acquainted with her brother-in-law.
The expression is ‘met iemand kennismaken’ not ‘met iemand aantreffen.’ The others encountered / found / met Dorine there. Dorine was getting acquainted with / getting to know her brother-in-law.
If you said, “Zij troffen Dorine aan met haar zwager,” that would be like saying they found / caught her with her brother-in-law, which I believe would imply that she and her brother-in-law were doing something together they shouldn’t be doing.