Hello again,
I'm so happy to tell you that not only did Bella appear this past weekend (after quite a long absence), she was accompanied by Carl, and the two were definitely enjoying each others' company over the weekend!! Whereas Lone Carl would typically have spent the entire weekend on my sand following me around, he spent most of his time in the water with Bella!!! I'm thrilled that Carl and Bella found each other, and I'm even more thrilled that they have decided that my place is big enough for both of them. I'm assuming that I won't be seeing any cygnets since there's no nest on my property, where they spent their weekend...
Thanks so much for all of your help!