If you haven't already, you should take a moment to introduce Siri to your family. Once you have done so, you can quickly ask Siri to message or call your wife or your brother without having to say their full name. If your spouse's full name is a multi-syllabic mouthful like my husband's, this can be pretty handy.
But first you're going to have to introduce yourself to Siri.
In order for Siri to know who you are, you will need to create a contact card for yourself in Contacts.
Once you have done this, go to Settings>General>Siri. Tap on My Info and select your name from your contact list.
Now you can start introducing people to Siri.
Press and hold on the home button to open Siri and state the relationship you want Siri to remember. For example, I might say "iPhone Life is my office." Siri will ask me to confirm the relationship and from then on if I want to call iPhone Life I just need to say "Call my office."
If you have more than one of the same kind of relationship, like multiple sisters or brothers, use a qualifier like "younger" sister, "coolest" brother, etc. when you are adding a relationship.
To edit or remove a relationship (maybe your other brother found out he is not the "coolest" brother or maybe your girlfriend got tired of you talking to Siri so much and dumped you), go to your card in Contacts, tap Edit in the top right corner, scroll down to your list of relationships, and tap on the delete icon.
