Nationality Help

After i went uk in march 2013, FIR has been file against my grandfather under IPC 419,468,471 on march 2013 and i am co-accused in that case so when i went india in feb 2014 the immigration officer caught me on mumbai airport as FIR was filed against me for using forged documents. Actually the main accused is my grandfather and all below 5 people are co-accused. FIR state that my grandfather has used forged birth to obtain portuguese nationality and therefore whoever obtained portuguese nationality through my grandfather is counted as guilty. i did my nationality through my parents marraige certificate. My father obtained portuguese nationality in march 2013 as he is portuguese born 1960 in daman. As per law i can have portuguese nationality if my mother or father is portuguese. My grandfather is not found guilty yet but even if my gradfather is guilty or my mother nationality get seized, i have right to have portuguese nationality through my father. I was not involve in my grandfather documents process as i was under 18 when he obtain his portuguese nationality. police dint file chargesheet till now. my documents and my parents documents are all geniune and i can prove that but the case is not going further. what should be done now? need advice and help please.