Harrison is 100 x the player Donaldson is, and always has been. Tahs could do no worse than to replace Harrison now.
On tonight's match, Nic White gave a master class of No 9 play when he came on. Brilliant as Tate was and is, Nic needs to be the Wallaby No 9 for his experience and cool head. Tate to learn from him and come on with 15 to 20 to go.
On what basis do you rate Harrison 100 x better than his backup Donaldson? I don't think The Waratahs would think this. The Mack Mason experiment failed due to never giving him any game time, so I don't think they would do this again by signing a replacement 10 who is 100 times inferior.
I also note the other franchises are giving their back up members starting positions to see what they can do. The Reds have used all three half backs, The Brumbies gave Ryan Lonergan a start plus the Rebels shifted Deegan into 10 and pushed To'omua to 12... If ever there is a season to do this, it is this year, because it is a 4 team comp with The Force hampered by a lack of decent cattle, and no Kiwi sides. Harrison is good but if he is injured how do we know how good Donaldson is?
I agree with your comment about White starting, however McDermott's willingness to constantly look for a quick tap to catch oppositions napping ala Aaron Smith to me is a must skill of a quality halfback. Aussie teams do not often factor this into their game plans.