To dream of your sister-in-law symbolizes attributes that the both of you may have in common. Also, contemplate the bond that you both share.
If you are arguing with your sister-in-law, it may imply that you refuse to accept that you both have certain aspects or attributes in common.
[1]See Also: People metaphors also see Brother-in-Law.
[2]1. Religious church; Natural sister-in-law.
[3]Same as Sister.
[4]