How to transport changes to very large ODSes in SAP BW

Almost all BW systems which have been live for 3-4 years , it is a standard sight to see the following :

1. ODSes like Delivery Items , Material Movements etc having millions of entries ( this of course depends on the usage of these functions in SAP )

Very often a change request comes along which requires an enhancement to these ODSes and in lieu of the the time this would take - a lot of sister ODSes spring up all around these mega ODSes leading to a proliferation of Infosets and cubes and Multiproviders.. which in turn lead us into very difficult data modeling choices