Can you be cuckolded by your sister, even when you've never fucked?

In my fantasy, she's a gorgeous girl who's been lusting after her hunky, well hung, nineteen year old brother for as long as they can both remember. She flirts with him mercilessly, trying to get him to bury his long thick, hard cock in all her holes, but although their desire is clearly mutual, he knows it's wrong, and won't let things progress. She's managed to get him to masturbate with her (but no touching...), and she's even persuaded him to let her watch him fuck his girlfriend, but she can't get him to fuck her and form the loving bond we all know they need.

Then she has the inspiration to invite two or three of HIS friends round and (perhaps by playing strip poker, or perhaps by playing 'truth or dare') gets them to fuck her in a steamy gangbang, which she gets her brother to watch, and perhaps even to film, very closely.

He is intensely jealous, very, very horny, (so effectively cuckolded, without the humiliation or the small dick), and she eventually gets him to eat all his friends' cum out of her well fucked holes, and (maybe...) give us a happy ending by making her rear end very happy too....

Whadya think?

:-)