Oh my, sorry things got more complicated for you! You did the right thing making sure everyone's beaks were clear and keeping your humidity up as high as you can. Let us know how things look when you get back from work. If there are still blood vessels in that inner membrane around the ducklings, you really can't do anything else to help them yet. Those need to disappear first before proceeding. Once the blood has been drained from those, the yolk sac will also be absorbed and the ducklings will be ready to hatch. Helping any more before that point will most likely not end well for the duckling.
Here is the link venymae mentioned about assisted hatching. It's always a last resort, and always best for the ducklings to do as much of the work themselves as possible. It's alot to read through, but it tells you what to look for and then when and IF you should help: