The wife of the third couple that we first swung with started kissing Mrs Afterwork's nipples and they began to exchange those actions. As encounters increased Mrs Afterwork was the first to go down on the wife which became a 69 event. Eventually, the ladies would often keep things going while the guys recovered. Both enjoyed cream pies as yes,in those days, we were bareback.
During one group grope, the husbands succumbed the the ladies demands to take turns with the ladies sharing the other husband to gauge the apprehension factor. The fellows found no apprehension with one swallowing a load on the very first attempt, but it wasn't and remains not a desire. Rather more of a participation that seems to really turn on the wives and is comfortable for the husbands. The guys have also become very comfortable masturbating each other while watching the ladies share double headed dildo. Sometimes it results in ejaculation rather than "maintenance" to be ready for the ladies.
We have been with that same couple for decades and our practices remain the same. Guess we are bi-comfortable among the four of us for the fellows and the wives are very happily bi-comfortable with the other ladies during all swing situations. We seem to find that other couples seemingly are receptive to observing bi ladies, but we don't test the waters with bi males and thus far no other couples have broached the subject.