Is it permissible to shave one's beard in obedience to a father who threatens to disinherit his son, orders his daughter to stop studying, and commands his wife to abort her fetus and leave the home?

What we see is that the sum of what the questioner mentioned concerning his father's threats if he refrained from shaving his beard, regarding himself, his sister, and his mother: this is considered an excuse for him to shave his beard, as long as his father is capable and determined to carry out those threats.