I don’t think there are any other methods - you must recreate the original return in TaxCycle, save a snapshot, then make the corrections and file an amended return. There is no “Change My Return” for T2s on RAC like there is for T1s, and I don’t know of a “T2-ADJ” form like the “T1-ADJ”. Perhaps you could send CRA a letter detailing the changes, but I’ve never tried that.
@mazhar When T2 return is adjusted, you are resending the entire return with revised figures. So, as mentioned by @Nezzer, there is no T2ADJ form.
So, to adjust a T2 return, the first thing is to make sure that the initial return was assessed. Then, all you need to do is to indicate in Info that you are adjusting the T2 return, provide the reason for the adjustment in T2ADJ form and transmit. Very simple.