GST on CHS

XYZ (Cooperative Housing society) is of about 10 buildings and each building is a separately Registered Society.  All these buildings are managed by a federation. Federation consists of members from these 10 society only. Federation bills these society a consolidated bill for common maintenance. They charge GST for this. Whereas individual member society does not charge GST and therefore this GST is total loss. To avoid GST loss, 1) can the federation bill individual members and since the individual members bill will be less than 7000/- no GST. 2) Individual society will issue bills to the members and since the individual members bill will be less than 7000/- no GST.