Manual bedtime range option for automatic tracking

Could you add a manual bedtime range option for automatic tracking to start and stop, rather than rely on alarms and desired sleep durations?

I’m using sleep as android to monitor my son’s sleep. I use a dedicated android device and want to use automatic tracking.

I have been able to set it up using a silent alarm and a desired sleep time of 12.5 hours but find this a little impractical. He sleeps around 10h but I have to set a longer desired time to cover late sleeps so tracking doesn’t stop. I have had to disable the default backup alarm for this purpose - but then I can’t use it when required. Can you add an option to just specify a bedtime range?

I understand there is a default range but it doesn’t fit my son’s patterns and doesn’t stop tracking automatically. It just keeps tracking all day. A range would allow it to start and stop without manual intervention, keep the backup alarm functionality for actual alarms and the desired sleep time consistent.

I want to set up a similar configuration for my grandmother, with a light phaser mini, but really hoping you can add the manual bedtime setting for this to work.