What are the requirements and process for extending a 60-day entry visa in Thailand for a family with a baby?

A US family in Thailand seeking to extend their 60-day visa can apply for a 30-day extension in Bangkok when they have 45 days or less remaining on their visa. It costs 1,900 baht per person, and children under 14 do not require an extension as they cannot be fined for overstays. It's not necessary to provide exit tickets for an extension application. You should prepare the TM.30 form from your accommodation, and if staying at a hotel, request a printout of your registration. If staying privately, ensure the host registers you online. Passport photos are not needed for the application if all family members are applying in person with their passports.