What is the Catholic Church's teaching on paying respect to one's in-laws? The fourth commandment says that one should respect one's parents. I wish to know if the Catholic Church has made some rules which would govern one's conduct towards one's father-in-law and mother-in-law.
What is the catholic Church's teaching on paying respect to one's in-laws?

Did not Our Lord say:  


  “A new command I give you: Love one another. As I have loved you, so you must love one another. By this everyone will know that you are my disciples, if you love one another”. (John 13:34)


In-laws are simply our extended immediate extended family through marriage.

Our Lord also said:


  Love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength.’[a] 31 The second is this: ‘Love your neighbor as yourself.’[b] There is no commandment greater than these.” (Mark 12: 30-31)


Do not forget that we must love and respect all people, strangers, in-laws as well as those we do not get along with. The Golden Rule applies to all people including our in-laws.


  "Do unto others as you would have them do unto you". (Matthew 7:12)


The Fourth Commandment says that one should respect one's parents. In-laws are family by extension of marriage and they deserve our love and respect. It behooves us as Catholics to follow Our Lord’s words to the best of our ability.