Spanish to Dutch Other Law (general)

Hi everyone,

I'm translating a Cuban document 'certificado de residencia' from Ministerio del Interior Dirección de Identificación, Inmigración y Extranjería and I read the following in Spanish:
My. Sida Lilian G. Pérez, 1er Oficial de Trámites: Oit Guantánamo

Can anyone tell me
A. where the abbreviation 'My.' stands for?
B. how I translate '1er Oficial de Trámites'?

I've already found an entry here stating court official/court officer but a Cuban friend of mine told me that 'Oficial de Trámites' was the first official procedure of handing of a certain legal document. All help very much appreciated!