A Chipped Cup, if you notice, we all agree on that.
The question was however, why is REGINA helping her, since the only reason why she joined her mother was to get Henry back and she shouldn’t be trusting her in anything. The only possible reason would be to eliminate Gold so that he cannot threaten Henry. I’m also a fan of the theory that Cora knows all along that Bae is Neal (I cannot see him being anyone else) and when she reveals it to Regina, she might freak out she will lose Henry for good?
From what we’ve seen, I don’t think it would take much for Regina to fall into Cora’s trap.