M is the father of L. R is the father of M. Q is the husband of S. L is the brother of Q. How is S related to M ?

Daughter - in - law

ATQ, 

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Please note:

  l   ⇒ Vertical line shown "generation gap".

 =  ⇒ Double lines shown "relation of spouse" 

—  ⇒ Horizontal line shown "relation in same generation other than spouse".

     ⇒ Rectangular box shown " Male".

     ⇒ Circular box shown " Female".

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