Replace existing datasource with new one

Hello Experts,

I have a situation where I need to change the exisitng datasource(0FI_GL_4) to new datasource(0FI_GL_14).

Currently existing datasource is loading to DSO and then to Cube.

I am told that we should be using same DSO and Cube. Now my questions are :

1) Is there any thing in particular i should do as I will be having 2 datasources under existing DSO(one will be switched off. The agreement is we go live adding the new datasource but will be switched off for certain time. Then we switch on this and switch off the old one)

2) Do I need to do anything to make sure exisitng data (loaded with old datasource) remins even after we start loading using new one as the new one is just a replacement, but reading from different tables.

Your help is much appreciated

Kind Regards

Shanthi