Garfield was in on it. Adrien found the Miraculous shortly before Renard appeared. Several months later, Garfield found out, and they'd been switching ever since.

When father just appeared from our perspective, it was a shock. Didn't trust it. But Garfield came up with the idea of us both jumping Ladybug at once since we didn't need the Miraculous to transform, and it'd catch her off enough for us to hopefully get at least one earring.

We knew how to get Ladybug. We were waiting to somehow lose father again. And I....I decided that I wasn't going to let it happen. You were new, I could win if I just stopped caring about the consequences, we could get them quickly, make sure we didn't lose him, and maybe figure out how to get her.