Therapy/ service dog replacement pup/dog

My mum Jo has multiple disabilities (neurological lupus, motor neuropathy affecting her legs, spasticity in her muscles, difficulty walking, problems with her hands etc) and her therapy dog needs to retire soon. We need to source a puppy and train up a new dog to take her current dogs place (although of course Zach has a home with her for the rest of his life). The new dog will be trained by an experienced therapy dog trainer who will teach him basic manners plus the tasks Jo needs to stay independent (walking with her in harness, picking things up for her, bringing her emergency medications etc). Jo has worked in domestic violence for years and it is time we give back to her.