You could stake the property lines yourself, but the neighbors can still dispute it. If you want the matter settled once and for all, the property lines need to be re-staked by a professional land surveyor.
The fact that you retain an official land survey will really help you in this situation. Call the company that did the original survey and ask for a quote on re-staking for a fence land survey using the original information.
A typical land survey costs around $600; however, using the same company for just one line of your property will only be around $100.
Once they stake the property, we suggest installing your own fence or at least putting up something temporary, like heavy potted plants. This way, the line is marked and you and your neighbors won’t have to re-visit the situation again.