Identity verification

Hello - I applied for my 2 Children’s renewals on the 24th April - one needs an adults as has just turned 16. I did it at the post office on their digital form and was advised no other docs or verification was required. However today - over 3 weeks later they’ve asked for someone to verify their ID and I’m now really worried they will get lost and hold it up further. I am travelling in the 2nd of July 😩