Migrate the complete solution along with data from BW 2.x to BW 7.x

Dear Experts,

There is a scenario in which SAP BW 2.0 have been upgraded to 7.0 version, while the BW flow and the custom models that exists are still in 2.X version

We acquired separate SAP BW 7.4 powered by Hana , We would like to migrate the older version of BW i.e 7.0 with mentioned content and models into this new system with data and going forward our organization would like to have only one system and dismantle the old system . Please let us know the process in the form of steps as to how it can be achieved . Need your expert input on this .

Thx,