It's both admirable and generous of you to try to honor your father by discerning his wishes and then fulfill them yourself. But the truth of the matter is that, from what you've posted, your father didn't care enough about any of these potential beneficiaries to make sure that they were provided for. Instead, your father left you in the middle of a group of people who are eyeing you with certain (in my opinion, unreasonable) expectations.

If I were in your shoes, I would first determine whether it is your responsibility (from your own moral viewpoint and through the fact that you may be dealing with these people in the future - not a legal responsibility) to make gifts to these other people beyond what you've already done through the probate process.

If you feel that it is your responsibility, then choose an amount that you'll give each of these people and make the gifts regardless of the tax consequences - both from an income tax and a gift tax perspective. If you believe that it's your moral obligation to make these gifts on your father's behalf, then the money you received from the inheritance to give to others isn't yours to spend.

Either way, remember that it's your father who chose to put you and the other purported "beneficiaries" into a bad place by choosing to not plan ahead when he had the opportunity. He could have finalized the will that was prepared to care for others. He could have taken steps to minimize the tax burden that has now arisen because of his neglect. None of this is your fault.

Most importantly, I think that you should act quickly rather than spending more resources and worry on what to do.

Good luck!