Case study question, help explain why I’m wrong.

Case: A 38 year old farmer and his two sons (16 and 14 years old) in Thailand died from acute respiratory infection with intense infiltration of inflammatory cells in the lung tissue. Analysis of the lung tissue revealed no indication of bacterial or fungal infection, but identified an H2N5 RNA enveloped virus in the farmer and his sons. Further analysis of showed that the wife of the farmer had an H2N3 virus, their poultry had H1N5 virus, and their swine had H2N5 virus.

Question: It appears that an antigenic shift occurred. Specifically, how, in this case, did it happen?

My answer: In this situation, it is likely, that the virus from the husband/sons/swine came together with the virus from the poultry to create the new virus within the wife.

Teacher’s answer: No, the shift likely occurred in the swine.

My reasoning: the case stated that the husband and son’s died of the SAME influenza virus (H2N5) that the swine had. However, if an antigenic shift would have initially occurred in the swine, the swine would be shedding the newly created virus, so wouldn’t the husband and son’s be infected with the same virus as the wife? (H2N3) Whereas if the antigenic shift occurred within the wife, then when she was tested, she would be shedding off the newly created H2N3 virus that she tested positive for, (likely from the swine virus and the poultry virus coming together), and that would explain why she was the only one shedding that virus?

Please help me see how it would have occurred within the swine. I love micro and want to fully understand everything. Thank you if you’ve taken the time to read and reply :)