Billing Price (EA89) with 20 decimal positions

We have a requirement from a customer to use "a minimum" of 20 decimal positions in the prices used to bill energy to customers.

I see that only 8 decimal positions are allowed in the standard.

Does any of you know how to deal with this situation? I don't know if there are any way to enhance the EPREIH table PREISBTR field that have 8 decimal positions only.

Maybe a combination with operand values can do the trick but I would like to hear any idea.

Thanks,

Fausto