Procedure to transfer the property in case of two nomination

My father expired on 9th october, 2016 and he have made nominees as first name my mother and 2nd name myself(daughter). I have applied to the society to transfer the flat in my name. I want to know the full procedure how to transfer in case of two nomination. What will be required. As per my knowledge they told me to give the Appendix 15 and 18 (indemnity bond of rs.200) because of two nomination. Can i transfer the flat as joint holder. For that what will be procedure? I have to give noc for transferring the flat on my mothers name then she have to make a nominee of my name. I am not getting appendix 15 and 18 form in Mumbai. Should i prepare it? religion : hindu