Agreed with talant
There are too constructs that say almost the same thing:
If only I had known you were ill, I would have come sooner (truely lamenting)
Had I known that you were ill, I would have come sooner (clarifying, stating)
So mixing the two
If only had I known you were ill, I would have come sooner
It sounds a little strange but the meaning is clear - you regret not coming sooner. I doubt they will penalise you for it though.
Jack
👁 Smile :)