Is it essential that all passports have thumb impression/signatures. In my case Passport office never emphasised this and issued us machine readable passports without signatures/thumb impression on some passports.
For adults, passport officer at the time of delivery tells to sign so please sign on your passport too.
For children, I think thumb impression is not required because at the time of making passport the passport office waives thumb impression for children.
By the way, have you received PPR2.