Urgent Help Needed! Passport forgotten!

Hello, today right before closing we mailed our spouse visa to UKVI centre in sheffield. Later we discovered (very stressed) that my wifes passport was forgotten.

What do we do??? I dont want it to be rejected and would mail it if possible but cannot just do so blindly and how would they attach it/merge it with our application? Write the same GWF number and instructions on the front?

Do we contact them and how if thats the case?

If not then what?

They need the passport so do we hope they ask us to mail it later.
This is literally our life savings and a ton of work as im sure you know. Would hate it to fail on technicality. Any advice is helpful, thanks, Lewis.

Send your passport by recorded /registered delivery to the exact same address as you sent application with a short explanation of the circumstances...BUT make sure you quote the GWF refs number that was on your application. I am sure they will attach your passport with your application on receipt of it.