To dream of an in-law represents compromise, abiding behavior, or decisions with a stronger interest in avoiding negative situations.
Like all people in dreams they may also symbolize personality traits in you based on your feelings, opinions, or memories of them that stand out the most.
To dream of having sex with an In-Law represents an enjoyable waking life experience you are having with a compromised decision. Liking something that isn't your first choice a lot.
*Please See Father-In-Law
*Please See Mother-In-Law