Any Extortion Laws that can be applied to a Landlord/Tenant situation?

[Amber Fiery]

My Grandmother-in-law and her daughter (Power of Attorney) sold the house out from under my father-in-law, my husband and myself. We had prior arrangements with her.  One was to take care of her son, my father-in-law to include his living expenses.  I spoke to my grandmother-in-law on May 21, 2015 and asked (before it was sold) what we could do to keep us here so my youngest daughter could attend the HS as she went through the elementary and middle school and knows nothing else.  Well my father-in-law and my 2 adult daughters witnessed the conversation.  My Grandmother's P.O.A, called her brother (my father-in-law) and stated that if we paid the past due property taxes that was around $2700 that we could continue to live here for up to six (6) more months.This was on June 1, 2015.  Come to find out that the house was already sold on May 18th.  Would this be any kind of attempt to extort? They were fully aware the house was sold on the 18th but still trying to get us to pay a property tax that is now on the burden of the new owner.  Also, in 10 years living here, we have never been responsible for property tax.  

I hope someone can shed light on this.  

Thank you in advanced!!

A. Fiery