Scales for Allocating Stationary Hospitals, CCS and Ambulance Convoys in 1918

[Sappersnooper]

I have tried to search existing threads but with no success. There was a scale for allocating Field Ambulances to a division but I am seeking info on any scales for the allocation of stationary hospitals, CCS and ambulance convoys in 1918. If so, was this at Corps or Army level? I have found actual allocations in DMS war diaries but there seems to be no mention of a fixed or normal scale. Thanks for any responses.