Short sale New York/ Nassau county

[Jack Khorr]

Trying the short sale a property, owner / father passed away. Found the kids and wen into contract. All of a sudden we saw the property on MLS in New York/ Nassau county listed by the agent for sell and now found out the father in fact had a girlfriend and left a will that gave her 65% and his kids 35% of proceedings. The house is abt to go on foreclosure . How should we approach this situation. The girlfriends agent is going to court to get probation which will take 2-6months . He wants me to get signed paper from kids to agree to short sale. Aren't We suppose to sign contract meanwhile? What's the best way..... Need help with short sale.... should I take step back from this deal????