Thank you for the response.
Before posting the query, I was also thinking of the same. However, the question raised because of the difference in the SFD for primary and secondary beams, though both the members are subjected to a single concentrated load. If you refer to the snapshot attached in my original post, Primary beam is showing the correct diagram (which is subjected to a concentrated load transferred from the secondary beam) whereas the secondary beam is showing the incorrect diagram (which is also subjected to a concentrated load only).
Before posting the query, I was also thinking of the same. However, the question raised because of the difference in the SFD for primary and secondary beams, though both the members are subjected to a single concentrated load. If you refer to the snapshot attached in my original post, Primary beam is showing the correct diagram (which is subjected to a concentrated load transferred from the secondary beam) whereas the secondary beam is showing the incorrect diagram (which is also subjected to a concentrated load only).