Mabuti na tanong ito kasi marami ring nag-confusion dito, honestly, best to ask directly sa parish office or civil registry kasi they handle the legal side, pero from what I know ng few mum friends, the baptismal certificate itself ay hindi na mababago once recorded na, pero ang civil documents like birth certificate ay pwedeng i-update once magpalit ng surname mo after kasal. Siguro pwede ring mag-file ng petition to change the surname sa birth cert at records, pero alam ko na may process and requirements yan, definitely worth asking the professionals para sigurado kayo ng exact steps, lalo na since binyag pa lang next year anyway!