@imsak,
Quote: Do I use the term 'make believe' ...
First, DO is used to ask about a general condition, an habitual thing.
Have (Do) I used the term 'make believe' ... ?
Quote: - I then suspected what they were doing toward me was just a make-believe story to deceive money out of me.
- I then suspected what they were doing toward me was just a make-believe story to deceive ME out of MONEY.
In your second one use MAKE BELIEVE.
In the third PRETENDING sounds more natural.