I do agree to sell what the customer wanted. I would be upset if the salesperson tells me to buy a different camera than the one I ask for. I fully believe that one should do his/her own research and make his/her own decision on which to buy.
The OP hasn't come back to respond in either thread regarding blank frames since the specific question about edge markings, so I vote for fix before developer.
Yes there was edge marking on the film i.e where the film was pulled to put onto the spool it was slightly darker. Also there were no markings, it was completely blank
In case he actually fixed at first step and yielded some halide retention at the edges due to contact with the reel which in combination with edge fogging resulted in dark patches at the edges, then we on our side should think about that ambivalent term "edge marking".