Step one: Open up 2 of your accounts, (One parent one child or BOTH PARENT!)
Click Parent on the account you wish to have chat on IF its a child one, then refresh. If your allready a parent, make them a child.

This tutorial is mostly for people with 2 adult accounts:

Step 2: You have done it correct it should be like this:

Step 3: Next click SAFE on the chat section on the account who doesnt have chat for the one who needs chat like this, then click full:

Step 4: Now you have chat!