How do you handle general voicemails with a small team?

I'm B2C. We do most stuff over the phone with elderly customers. Just brought on a second assistant to help out.

My first assistant is family - been with me forever, is elderly herself, and is infuriatingly bad with tech. She can use google calendar and webmail. I tried to get her to use outlook, it was a disaster. She can't drag and drop, she refuses to use anything other than a track pad and can't manage to keep the track pad depressed, so we gave up on file management.... A computer is basically a web browser and that's it. However, customers love talking to her, so at least she has some value.

Right now our general voicemail box emails her transcriptions (with the audio files). Now that I've got assistant #2, I want her handling voicemails too, but I need to figure out how to split it up so they're not both calling the same person back.

Any ideas on how to set this up so there's no overlap? I'm considering a shared inbox, but expect my assistant number 1 to manage 2 inboxes is anxiety inducing.