It might be too late -that's the realistic stance.
The secondary response is yes, they can.
BUT
If you want to use MCs to have an uncapped year retake, the onus is on you to demonstrate significant MCs, and why you could not disclose these at the time. It is the last part which usually provides the sticking point. I don't know your circumstances, but maybe you can work it so that the latter point is minimised. It's hard to do this, in my experience, but it is worth a go.