Panhandle, TX Estate Planning Law Firms & Lawyers

There is a lot to unpack in your question. Did your father have a will? Did you (or anyone) report your brother's theft while your father was alive? If your father had a will, you need to bring it to the attention of the probate court where he died. If he did not have a will, you will likely need to handle his estate through a process known as administration. Because you mention undue influence and breach of fiduciary duty, I assume your father had a will in place. But I could be in error. In any case, please contact an estate planning attorney as soon as possible to prevent further waste of your father's estate assets.

Nope. I do like to put a statement in the wills I draft that the testator chooses not to leave anything to the child. That way, there can be no claim that you forgot them. It is your money and your assets, you can leave it to whomever you want.

If all you have is non-probate property, all you have is property which does not pass under a Will.  In that circumstance, you do not need a Will.