BUDGET_REF - to use as a normal chartfield

Hello - we have already used up CHARTFIELDs 1,2 and 3 provided in the tables but users still want to add a new chartfield. There's BUDGET_REF in the different tables which we think we can use. Given that this is for Commitment Control module, can you advise if we will be successful in using this field for a different purpose? i.e. to treat BUDGET_REF just like CHARTFIELD1 for instance, in terms of its use in the system and not as a field used in Commitment Control module.