Ancillary Probate Procedure

Have a question on ancillary probate procedure in Oklahoma . The wills of our deceased relatives were probated in Texas. We were told we could not be paid royalty once production starts on our current lease since these wills were never probated it OK. If this is the case can go before the court with the certified will from Texas and have it probated or do we have to have an attorney do this. If we have to do the later can anyone tell me the approximate cost and any recommendations on attorneys in OK.