Don't know about an actual real life threesome but during a stream once (I think) someone asked her how many guys she could fuck at once. She said 6 guys because she has 3 holes, 2 hands and then laughed not knowing what the last guy would be doing.
Doesn't answer your question, but given that she's DP'd herself on stream before (and came hard from it) and described how she'd like to get gangbanged, I'd honestly be surprised if she's never had a BBG threesome.