fake, ersatz, faux, phony
Here are some more: feigned, false, fake, artificial, bogus
There is no one-word substitute in English for "son-in-law."
The word you want is florist.
Sportsmanship is a word substitute for spirit of game
The word metalworking is one word.
eat, use
One possible substitute for "their" is "his" or "her" depending on the gender of the person/people being referred to. Another substitute can be "its" when referring to a non-human object or entity.
The word that works is idiot.
The word "genuine" is an adjective.
The superlative form of the word "genuine" is "most genuine."
Elevate
Traditionalist
Omnipresent