That is a good question, buddy..
But as per my knowledge if it is an open then it doesn't matter with a current or new employer. Having said that I remember my case where i did select same employer but along with open work permit.. It was also mentioned in the instruction guide that if it is Open Permit then you don't need to specify Employer's Details in the form. So i did the same.. left the employer section empty.
By the way, congratulations on approval and could you please share the timeline for your BOWP as I applied on July 11? and did you apply online or by paper?
Thanks,