Otherwise you will be double counting. If you apply the total nci percentage to the sub-sub’s assets and then apply the nci percentage to the subsidiary’s assets, thes a double counting. Part of the subsidiary’s assets is the subsid’s investment in the sub-sub’s share capital
That share capital (in part) represents the net assets of the sub-sub so not only will you be taking the nci share of the investment in the sub-sub, you will also be taking the indirect nci share in those same net assets of the sub-sub
Very difficult to explain all this in the written word – do I not try to explain it in recorded lectures?