Hi
1) Since the 1987 document was executed between the vendor who sold you the property and then predecessor owner and that there is a time gap of more than 30 years, the 1987 document cannot be amended even if parties are available.
2) Whereas the 2001 document through which you had purchased the property contains the correct boundaries,, your father during his life time should have ideally applied for rectification of boundaries through Revenue Divisional office/ District Registrar within 3 years i.e on or before 2004. However the rectification of boundaries was not done during your father's life time .
3) Since your father had passed away recently in the year 2016 and that more than 17 years have passed from the date of sale deed, you as your father's legal heir should approach the District court and file a suit for declaratory title on the following grounds:
a) Your boundaries in sale deed and actual location are matching and correct
and
b) You are in possession of the property since 2016 and prior to you, your father was in possession of the said property from 2001 and previously the vendor from whom your father had purchased has been in possession since 1987 and hence you and your predecessor's in interest are in continuous possession of property since 1987
and
c) That you have obtained building permissions(if available) and have been paying property tax, electricity bills etc since the year 2001.
P.S: Prior to filing of suit, you should get a FMB Sketch( Survey) done by Revenue Inspector at MRO office and submit the same with certified copies in the court.
Hope this information is useful.