Whenever someone dies their estate has to go through probate even if there is a will with specific instructions. The estate has to go through probate and there has to be an opportunity for anyone to contest the will. Yet the lawyer asked Oliver for a bank account number where the funds could be deposited and indicated it would only take a couple of days to transfer the money and that it just not legally possible.
This movie takes place just a few days after the last movie so when Oliver's biological father died Oliver was still married to Holly. It's not likely either Oliver or Holly even had time to file for divorce yet. So as his wife Holly should have received half the inheritance Oliver got from his father and yet she is never mentioned in the context of the inheritance. In the next movie Shane mentions that Oliver is "freshly although amicably divorced" but still nothing is said about Holly receiving any of the inheritance.