I recommend repairing the hernia prior to the BBL or at the same time. If the hernia is small, most plastic surgeons are capable of repairing it. Performing liposuction with a hernia present can cause severe complications depending on what is herniating out.
Best to either repair it before or repair it at the time of your BBL. You don’t want to have liposuction with a known hernia as it could result in injury.