Colorado title purchasing from 3rd party in California

I am looking at purchasing a trailer in California that has a Colorado title(party A) (tag is from 04) purchased by party (B) in California, non-op form filled out but not registered, sold to party (C) in California but not registered, parked in field. So we are Party (D). Party A and B have signed the title, party C has not signed yet and neither have we.



Anyone have suggestions for getting this trailer registered in California?