As you're probably aware, if you've been referred to Second Nature via the NHS, it's the NHS who has funded your place on the programme.
The only requirement they have is that you record your weight at specific time points (month 3, 6, and 9) so they can measure the effectiveness of the programme.
If you receive an email or phone call reminder about entering a weight reading, then it means you're within one of those specific time points. Please go ahead and add your latest weight reading to the app, either manually or using your SN bluetooth scales.