Track sleep activity with more than one sensor

I’ve been using a polar Verity sense for the last year to track my sleep. The battery life on it isn’t great but that’s really not that much of a worry for me. If I charge it every 2nd day it will last through the night for sleep tracking.

What I am trying to figure out is this:

If the polar Verity sense dies, can the sensor switch to the phone for the remainder of the sleep duration? And can this happen seamlessly?

This way there isn’t a massive set of non recorded data right after the polar sensor dies.

If anyone else has figured this out or has some solution please feel free to respond …