If you are not married at the moment you apply at the Lottery, I do not think you can mention each other ( but you have to mention your child).
Both of you can play without being married. The thing is that the probability of both of you being selected is really small.
Let's say, only one of you gets a NL, then you will have to face a choice:
_ you can get married before your interview date, then both of you get the GC.
_ you do not get married, only one of gets the GC, then the other has to be sponsored by the GC holder (which takes about 5years). ( but still, you would need to get married to sponsor the other one).
I do not think there is another way.
I was a 2005DV winner, had been with my boyfriend for 4years when played at the Lottery. I received the NL, we chose to get married. Now both of us are GC holders.