Purchasing a foreclosure and previous owner won't leave

[Joseph Duenas]

I'm in contract to purchase a house that was purchased over a year ago in a foreclosure auction by  wholesaler/ investor. The right of redemption is up, and the current owner is selling it to me with a significant amount of equity.  

Here's the challenge: The previous owner, who was foreclosed on, occasionally comes to the house with his son. They pretty much are in denial that the house no longer belongs to them. We tried to have the house surveyed yesterday and the previous owners (foreclosed on)  chased the surveyors away. The existing owner disclosed all this to me prior. 

Question: Does anyone have any legal or other recommendations on how I should deal with these guys after I purchase the house?   Do you seen any risk with purchasing the house, legal or otherwise? 

Thanks BiggerPockets!