Question:
HI,
My wife did a hefsek tahara but forgot to insert a moch dachuk afterwards.Is it me'akev bedieved?
Answer:
If it isn't the first day of her seeing blood, meaning that she started seeing the day before or earlier, then you can be meikel if she didn't do the moch dachuk.
Best wishes
Sources:
Y:D 196-1,2.