A father-in-law is read as judgement and approval from outside your own family. Tradition sees him as the question of whether you measure up in someone else’s eyes.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.