Mandatory Rate Fields

On a rate, please make the extra adult and child rate columns mandatory, OR populate 0.00 if the user leaves the field NULL.  

Several CRS systems require a value in extra adult in order to communicate property. Making this mandatory, or defaulting to 0.00 would resolve this. 

It would also be helpful when trying to change from 1 rate code to another in Rover, as if the first rate has an extra adult value, but the 2nd doesn't - we cannot change the rates.