Someone had to write a daled and by mistake wrote a hei. However the gag of the hei was written like a reish. Once they erase the "yud" of the hei and are left with a "reish" may they simply add an eikav onto the reish and make it into a daled. Or must they also be mavatel the tzurah of the "reish" before now writing the the daled.
I have tzaddidim l'can u'l'can however I'd like to hear from the olam first.