"Do not disturb" and "Silent mode" do not work as expected (?) with hearing aid

My mother-in-law has a hearing aid connected to her iPhone 16. Under Settings > Hearing Devices, there is a toggle for "Play Ringtones," which is currently turned on. When it's on, this is how it works: - If a phone call is incoming when Do Not Disturb and Silent Mode are both *off*, a ringtone plays both through the phone speaker and through her hearing aid - If she turns DND or Silent Mode **on**, then the ringtone does not play through her phone speaker, but *still plays through the hearing aid*. Apparently this is because the "Play Ringtones" setting overrides Do Not Disturb. On the other hand if the "Play Ringtones" setting is turned off, the ringtone never plays through her hearing aid, whether DND / Silent Mode are turned on or off. There doesn't seem to be a way to have ringtones play through the hearing aid, but *not* when the phone is set to Silent Mode or Do Not Disturb. That seems... weird? Naively I would expect that Silent Mode and Do Not Disturb would stop *all notifications*, regardless of which speaker they play through. Is there some way to configure things so that they work that way?