If she is on her back, her head will be tilted to the side most likely. Both of mine slept on their backs until they could roll over. And Ds1 had bad reflux.
And as for the couple...my heart hurts for them and this is in no way blaming anyone or playing down the death. But most cases where it was diagnosed as SIDS were really cases of asphyxiation from blankets, adults under the influence and co-sleeping or otherwise unwise sleeping practices. So know that as long as you do everything as safe as possible then the chances of actual SIDS is pretty low. Though I worried myself literally sick with both boys. It's how we ended up co sleeping. I wasn't sleeping out of fear.