Vent-I can't check your mail for you! (Long story)

I think I would stick to the certified mail. If she is choosing not to get the letters, that is not your fault. I guess the only thing I would consider changing is the visit set up? Is there a particular reason you go to a center vs getting together w/ her on your own? We are currently not doing visits, but we've done them at the park, restaurant, etc in the past. We don't leave the kids alone with her at all.