Property line problem

Gud day po. I would like to ask what legal action to do for this long time property disputes of ours. My wife and I acquired a lot sometimes in 2005 from Mrs Y. We made a deed of absolute sale for this and have it surveyed by a Geodetic Engineer. This lot has no title yet but have a declaration of property to Mrs Y's father( Her parents is already and she is the lone survivor) . Since then we make a move to make it title to our names but to our surprised it was not able to do so because a certain Mrs X claimed that the surveyed lot of ours encroach to her property. She claimed also that there is an error in the cadastral survey, that this lot sometimes in the past they have planted crops.The seller Mrs Y and Mrs X have their copies of the technical descriptions which they presented me during our settlement in the barangay. As of now Mrs X built a house in this site and ourselves have not occupied yet this property since we bought this. What shall we do? What legal action we will file to the court? To whom, is it to Mrs Y or Mrs X? We want this thing to be settled soon. Thanks a lot.

first, ask help from a geodetic engineer to understand the respective claims of x and y in terms of the area. then you have to research and understand the history of ownership. from there, the proper remedy will arise