Can I add the statistic?

Hello,
energy have an issue when the sensor is not available for several days in a row.
I would like to update statistics and add the mean water usage for the unavailability period day by day manually. Unfortunately I can only update the entity from statistic panel.
Do you know if there is a possibility to add the value for given date/time ?

many thanks,
Chris

It is not something HA support as default, but Frenck have made an integration called Spook that can do it.
It should be available through HACS.

Many thanks !