I think that the next time something occurs that leaves you in doubt, YOU be the one to report it to your agency-act like it is the first time you were aware of it...this way, it doesn't appear that you were the neglectful one. If the agency already received report on a situation, then, good, if not, then, at least YOU told them. And, whatever happens afterwards regarding those other nurses, let them be the ones to deal with it.
I had a similar situation with pediatric home health. I only worked this case on Saturdays, because I already have a regular fulltime job in a clinic. I came in and the mother told me that her daughter reported to her that while she was in daycare a few days ago, another little girl caressed her vagina. This client has a nurse around her 20 hours a day-including school hours. I am not saying that the nurse had to see it directly (this is pre-kindergarden, where children sit in a circle, drawing, doing other activities). The client did not report it to the mother until the night shift nurse gave her a bath (I guess the bath reminded her of the incident). In any event, the mother went to the school, reported it, got the parent of the other mother involved, etc... Meanwhile, the nurse that reported it and the dayshift nurse did not report it to the agency, nor write a note about it.
I, on the other hand felt this way...if the little girl remembered at the time she received a bath, and she is only 4 years old, what if she then, associated that nurse bathing her as the one that touched her inappropriately? I mean, all nurses have to bathe intimate areas on our clients. And, what if more happened to this little girl that no one decided to report because they weren't really supervising her at the school? So, I called the agency that same day, left a message, and made sure I called back Monday morning again and reported the situation. Now, it was up to those nurses to explain what happened, but I reported as I heard it. Whether those nurses were going to report it or not was one thing, but I was going to make sure that I said it.
I did eventually leave that case, however, it was for other reasons.