Firstly, I want to correct your understanding for the BIE. It is an interface Board between the Abis & BS interfaces not Ater.
For Huawei BSC32, each module contains 8 BIE groups plus a TTBIE. Each BIE group contains 8 High Way innetfaces except group number8 it contains only 4 High Way. One HW supports switching for 32 time slots. So, if you want to activate DHR for a site, then the number of time slots would be increased resulting in the increment of HW required.