External/Internal Gross Profit Calc

Hello,

I'm trying to calculate an External and Internal Gross Profit calculation based off a few conditions.

To calculate External/Internal GP, I need to allocate the ExtCGSOther group + OpExp using our UD1 MFGResale between External/Internal using an allocation basis of ExtMLBS and IntMLBS (with the exception of account 6123 which is 100% External).

I need this calculation to be on a dept by dept basis.

I'm not really sure where to start and I tried looking at Golfstream but couldn't find anything that fits what my company is asking me to build.

Thanks,

Will