Will requesting return of passport affect visa process

Hi, my parents lives in Karachi (Pakistan) and I have applied for US immigration for them - its been more than 1.5 yrs since they had their interview - US embassy in Islamabad have kept their passport and doing administrative processing (from last 1 yr).

I would like to know if we ask US embassy in Islamabad to return their passports as they need to travel to some other country, will this affect the process of immigration visa or they will simply return the passports and ask us to submit passports again once they have done with administrative processing and visa is ready to be granted?