Sorry, that was a poor choice of wording on my part. instead of writing that "its not uncommon", I should have wrote "its not unheard of".
The 2 things that give me pause in this particular situation are:
1) that RA had to suspect these allegations would be aired publically (and nationally), and would be an issue which would be front and center at the custody hearing. If they are true, or even believeable for that matter - certainly a judge will rule against him taking custody of his grandsons. Why would he even attempt to do so?
2) the family dynamics at the time of the allegations. Without knowing all the details, we do know that RA had custody of his 3 children from his first wife (for whatever reason), then married a much, much younger woman, then had a child (Laura) with her. This could have exaberated already simmering relationships. Shortly thereafter the allegations rose and his 2 previous daughter (7 and 10 at the time) left to go live with their mother. According to RA, the report from the "friend of the court" supports his claim. I'm not sure if this report was for the divorce or transfer of custody though.
Having said that, the allegations could of course be true.
This is what I was suggesting before - now in a more detailed manner.
ETA: there was an incident of a false allegation in my extended family, during a divorce, which was coached. While the actual accusor (not the coach) apologized personally to the accused, the matter was never brought up/discussed again within the extended family...so my outlook could be a bit weighted.