Unfortunately it doesn't work that way. Her income will not be counted unless it is quite significant (in 6 digits) and that his/their <u>household</u> income is quite substantial to your household income (which includes anyone living with you, married or not).
I went through this and my ex remarried. He's self employed makes close to nothing but she makes 60K+ (if not more). I get a measly 100$ a month and even though I've been in court about it, there's nothing they can do. PLUS if he pays any other items etc, that counts in the amount too. They base it on the T4 slips (in Ontario) and that's that. As for her income, it's listed when we go to court but it doesn't change anything, unless, like I said, she makes LOTS of money - too much for her to make on her own (qualifications, type of job etc) for example. For me, she was/is a financial consultant and her income corresponded to what she would usually make so it ended up being completely dismissed. Whether or not he played with the numbers from his salary didn't make ANY difference.
Maybe it'll go better for you but make sure you've really checked into it. They may have a house, cars etc etc but if it ends up being all credit and comparable costs to yours (a 250K house can have a 900$/m mortgage payment) which is comparable to a rent payment, you won't get anything out of it...
It's frustrating but believe me, been there done that.
