Additional funding options for equity rich couple

[Alma Mills]

My parents are retired and own 2 properties in culver city CA, in west los angeles area. One is a single family appraised at 1.3 million the other a duplex that was valued at around 1.1 million.  They put a 1st mortgage on their residence for 625k and are using it to remove the duplex and put in 2 beautiful 4 bed houses on one lot.  It will be worth over 2.2 million when done and rent for over 12,000 monthly.   The duplex has no mortgage when the project is finished They will put a mortgage on the duplex to pay everything off. 

Challenge is that they need an additional 200k to 250k to do project right.  They are not able to qualify for a Heloc due to low debt to income numbers.   They duplex has no current mortgage.  What kind of loan can they get on their duplex property?  Or on their residence etc?

 It's being framed now and will only lack finishes when funds will be needed.   They are building it as builder owners with our help and i know some construction lenders don't like that. 

Any suggestions will be appreciated.