Sorry for the situation, I agree with allinaugust, the timing was bad mostly likely.

The sister cannot have herself named executor. An executor (male) / executrix (female) is the person actually named in the will by the decedent. If your fil has a will, it's his choice who that person is.

If your fil dies intestate (without a will) then possibly your sil could pursue being named administator. The other heirs typically have to agree and sign forms in front of a notary attesting to this for the court to consider. The duties of an execector/executrix/administrator are essentially the same. To be prudent in consolidating assets, paying liabilities, reporting to the court, and then if funds are left, paying the heirs / legatees.

It is your fil's business what he does and the decisions he makes. With the vulture statement, it seems this has really upset him.

dl