Hi Chandu,
Generally we should not tinker with standard SAP and that's exactly when account determination comes in place for GL account determination
I suppose that you already have assets in multiple asset class having multiple account determination assigned to it.
What you can do it that take a dump of asset class and its account determination with GL account in it and re shift data from one asset class to another based on GL mapping.
Even though if you manage to have a Z development for it, what if new evaluation grps are added? how will you control it? who is going to take decision which evaluation grps are in which category? moreover rigorous testing will be required every time new valuation class is added
If you have significant time as well resources you can discuss the same with ABAPers
Hope this helps
Thank You
Nishu