Scripture says we are not to judge each other for the days we choose to worship. However, some Seventh Day Adventists seem to get rather pushy about insisting they have chosen the correct day, and claim everyone else is doing not just doing it wrong, but breaking a very important commandment. If she is SDA, she will probably not want to change observing a Saturday Sabbath. It is a big part of how they separate themself from the rest of the body. Ellen White is their guru "prophetess." She has been proven wrong on many counts, but that does not stop them from all but idolizing her.
Therefore do not let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration or a Sabbath day.