It is possible to study the master "Interdisciplinary Latin American Studies" in part-time. Here you can find the necessary information as well as the application form for a part-time study. Please note, that a part-time status might have influence on benefits that you get outside of university, as for example BaFög, health insurance, social security, taxes, permit of residency, etc.
Aditionally, according to Article 3 (5) of the examination and main regulations of Freie Universität Berlin from 08.22.2013, “a temporally variable course of study in order to allow students the possibility of e.g. course-related employment or attending to family obligations even without formal part-time status” is feasible.