I assume the husband is the primary applicant?
Unless the primary does something to lose the green card, the dependent(s) are still eligible to continue waiting for their own cards. Changing jobs after 6 months on the GC should not jeopardize the green card (but the "6 months after GC" is not a hard rule and there have been a hundred threads on the job change issue). So it all boils down to the primary keeping a green card until the dependent's case is decided (and of course, the dependents should not do anything to mess up their own process, like being convicted of a crime).