Archives are separate - meaning they are both distributed territorially and among the three parts of it . Also you will receive no information from vital records from them, and they do not do research per request, you can only go there and research on your own the secondary records like school records, local historical documents. You need to contact the municipal office in charge of the last place of residence of your ancestors, but my guess is that only a local researcher can try and obtain information for you - due to legal restrictions and the general lack of interest to reply or correspond with people in foreign language.