help with duck eggs hatching. PLEASE HELP!

Ok yesterday I had 4 welsh harlequin duck eggs in my incubator one internally piped but after 36 hours and no external pip it died in the egg. The other 3 never even made it as far as an internal pip before dying. I have 2 of the same kind of eggs under my broody duck and as of yesterday they both have internal pips but nothing external yet. I feel like the one from my bator that had internally piped if I had decided to make a small hole to help it maybe it wouldn't have died, however when I opened the egg to try and determine the cause of death it had not absorbed the yolk yet so I don't know. What should I do about the two my duck is sitting on? Should I just wait it out and see what momma does with them, this is her first time to go broody, or should I open a hole at some point? I don't want to lose my entire hatch.