Hello Reg
I have used Boulton's book extensively as it has some of the best maps. In addition to his description of the role of the 10th I also own a copy of General Middleton's book written a few years after the Rebellion "Suppression of the Rebellion in the North West Territories of Canada 1885. In his book General Middleton describes how he tasked the 10th as part of Lord Melgund's column to cross the river a few days before the fight at Fish Creek. On page 37 he describes the arrival of Lord Melgund on the East side of the river during the height of the Battle at Fish Creek " As already stated the first to arrive was Melgund himself with a company of the 10th Grenadiers, and Fiennes of French's Scouts, as orderly officer, having guided to the scene of the operations by Captain Hiag. In superintending the extension of this company Melgund was very nearly potted by a shot from a long range rifle, of which the rebels had several, and Fienne's horse was killed by a shot from the same spot as he was returning from carrying an order. Later on came more companies of the Grenadiers under Lieutenant-Colonel Grasett and the two guns under Major Jarvis".
At the end of the Battle as the Middleton's columns moved down to the river to form a defensive Biv site for the night, the 10th remained on the West side of the Coulee overlooking Fish Creek as a rear guard. As the 10th was about to move off to the Biv site themselves a mounted group of Rebells appeared. In response LCol Grasett order the 10th to about face and advance on the Rebels who promptly withdrew.
Hopes that answers your question.
Regards
CArrow