Permanent Residency for parents with a special needs US citizen minor, other reasons?

[NealDavid]

I know of a family of non-US citizen parents and three minor children who were born here. The two boys are from a previous relationship. The father shares joint custody with their mom and pays child support, insurance, etc. The daughter is through his current wife. His work visa will expire in 2 months as the current employer has made a corporate-wide decision to not extend work visas. He also has an approved I-140 petition for immigrant visa which was filed by his employer over 4 years ago but waiting for priority date to be able to apply for permanent residency. Unless the father is able to find another job fast, he will lose his lawful status. His daughter was diagnosed with a rare genetic disease at a young age requiring high level of specialist medical care-something not available in their home country. They are worried that if he is not able to find another job in this short period, they will have to leave the country. Thus depriving the daugher of the much needed medical care and also being seperated from the two boys. Does this family have any options to stay together? He has been in the US for 15 years and they consider this their home. They are law-abiding people, own a house here and simply nice folks. I feel sorry for them. P.S. they are looking for a good immigration attorney.