I'm here! I'm replying! It's only taken two weeks!
"Would you attempt to listen to what I'm telling you?" Demeter demanded from him with frustration. "I'm saying that I know she loves you. I have come to understand that my daughter feels for you and that I am trying to accept the way she is now choosing to shape her life with you in it."
As for whether they were breaking the rules, well, Demeter wasn't going to continue arguing that point, but she was sure in her heart that they were. Persephone and Hades were crossing boundaries that should not be crossed and there would be something to pay for that in the end, although Demeter could not yet see what that might be. (Quietly she hoped it would be something that would only effect Hades. She didn't want another reason for her daughter's tears, and she didn't want another season that ended in violence between herself and Persephone. Once had been enough for that.)
She wasn't sure, either, if Persephone would want her around during the winter. Being rejected by Persephone seemed the most painful thing that Demeter could imagine. In spring they were joined, connected, and to lack that connection... Demeter didn't know how she would feel about that.
"Do you think that I will not treat this child with fairness and love? Have I ever showed cruelty to your Makaria? Makaria who may not even be my granddaughter by blood but who is loved by Persephone like a daughter? I do not punish anyone for the blood they bare." (This was, of course, a lie. There was not an Olympian among them who hadn't, at some point, cursed or killed or doomed a bloodline or city for the acts of one person. Olympians were not known for easy forgiveness, but nor were they known for remembering this.)
Demeter had considered, on occasion, kidnapping Makaria to see what Hades would think. But never had it gone beyond a fleeting unformed idea of revenge. The child was sweet.