I think the daughters did speak to LE, especially in the beginning stages of this search. It's just routine, especially in the beginning stages of a missing person case. Now, if they continued as the months went on, hard to say. These questions from investigators, IMO, would have been more uncomfortable, more directed at perhaps BM. That would be tough and confusing for sure.
I might be odd one out on this one but I'm not a fan of PE calling them out, whether it's the oldest because of the G*M funds and an attempt to have them allocated for SM brother's search or saying recently they might have important info for LE. While they are not 12 year olds, they are, IMO, very young. Leave them alone and let LE work that. I don't think they will feel compelled, by unknowns to them, that have a show. Again, just my opinion.