Logic Needed - Merging Subclass

Hi All,

we need to merge existing sub classes into a new subclass as part of product reclass.

Existing Subclass      New Subclass

A                                 H

B                                H

C                                H

D                                J

E                                J

We have lot of measures planned at subclass level and want to convert data based on new subclass mapping.

Here we want to add values of subclass ( A + B + C) and move it to newly created subclass H.

Is there any utility or function we can use to achieve this?

Thanks