How are the loans structured and who is the servicer?
If it's significant liquid assets, you might have a chance with a cash contribution and I wouldn't take the listing unless the seller was willing. Also, ALL assets must be fully disclosed or it will be considered fraud.
I closed a HAFA short sale recently where a seller had over $7M in non-liquid assets. We disclosed all of them fully and they showed on the credit report. The seller was willing to contribute close to $100k.
To our surprise, when it was approved, the contribution required was ZERO.