Visit with niece and nephew

A couple weekends ago, I received a call from my twin brother saying that my nephew had been asking about me. So cute. He said "I haven't seen her in days!!!" It had actually been 3 weeks. But he's 6 so "days" is pretty accurate. It warmed my heart. I did make a promise to him to spend time with him. Sometimes it's the only way to get out of their house without a child wrapped around your leg! I definitely feel like a superstar at their house. Not so much at my house. haha. Anyway, I made arrangements to have Penelope and my Mom go stay at my parent's house for an overnight so I could have my niece and nephew over. I had talked to my brother about it in the past. The kids wanted to see my new place but with not being able to see Penelope, it's never happened. The only requirement was that I had to "get rid of Penelope" in that I had to remove all pictures of her, anything that would remind the kids of Penelope and put it in her room and then lock her bedroom door so the kids couldn't get in there. I understand. They don't want to trigger any deep seeded trauma from Penelope's sexual assualt.
The thing is, after this visit, I really don't know if that's possible. First of all, they were happy little buggers the entire time. well, excluding when they fought over how they wanted to divide my time between the two of them when they didn't want to do the same thing. We made pizza, watched a movie, played games and did crafts. But almost the entire time they had questions about Penelope. First, I have to navigate the lies my brother and his wife told their kids about Penelope. I first learned about the lie a few months ago when being interrogated by my just turned 4 niece who of course assumed it was true and I already knew that Penelope lived at a "camp" (residential care facility or jail depending on what their parent's definition actually is) and not with me. So they wanted to know where I keep Penelope's things now? When do I get to see her? How long is she going to be at the camp? When are they going to get to see her? Where is she right now? (That was based on the fact I didn't pick up on the lie right away and had answered a question -months ago mind you - that I do see her everyday.) I tried to answer their questions honestly but without breaking the undisclosed rule of telling them the truth. My nephew asked "Where is Penelope right now?" I said "She is at Grandma and Papaw's house." He said "She is? That is so wierd! Whenever I go there, she is never there!" But, I try to re-direct them to their parents for answers. That's what I've been told to do. Not discuss it with them but to re-direct it. But that's the problem. Their parents won't answer any of their questions either. They feel that they are young enough you can talk these circles around them and they will forget. They want these kids to forget Penelope ever existed. If she doesn't exist, it never happened, If it never happened, than my brother didn't fail his kids by not protecting them and allowing them to be hurt. That is what is going on here. I get it, I do. I think I grieved my brother's pain as much as I grieved for my niece and nephew. He was the one watching the kids when it happened.
Not during this time, but the time prior to that, my nephew asked me "How old will I be when I get to see Penelope again? Will I be 6 still? Maybe 7? Maybe I will be 10. What will I look like when I am 10? I guess like a 10 year old." It broke my heart.
These kids know something is big time wrong and it revolves around Penelope but they don't know what it is. And they are full of innocent questions.
I talked to Penelope's therapist about it. Just because it really bothers me. I love my niece and nephew just as much as I love Penelope. As I told my brother once, I would do the same thing for either one of them I have done for Penelope. I am worried how this is affecting them. She was saddened by what I told her and feels that what they are doing could be more harmful than what Penelope did. "Dishonestly will lead to dissension" she said. They don't see what Penelope did as traumatic. They only know the Penelope that is their cousin who they loved and adored - and still do. And now, no one wants to talk about her to them. I told her that my brother said that their intentions are that the kids never see Penelope again "in case I never made it clear to you." Penelope's therapist and I both feel that is just really sad because it doesn't have to be that way. She feels the hangup is the parent's hangup and they are inflicting it on their kids. I'm not saying trust Penelope around the kids without an adult present in the room watching what the kids are doing. I will never trust Penelope at that level again - just in case. But is this better for kids? Do they need to go through the loss of their cousin? If so, then they need closure. She recommended that the kids write goodbye letters. But really, would that do it? Penelope is not dead.