Child Support from a Low Wage-Earner

My question involves a relationship in the province of: Newfoundland

I am engaged to my future husband. We have 3 children in our blended family, 2 mine and 1 his. We are established and content and have our children most of the time.
His ex girlfriend(they were never married) is still living with his parents. It is a situation that is taxing on everyone in the family. His parents would like to be free of her as would we. His child is 13 and has been living with us full time for 3 years. We did speak to a lawyer in December last year and he recommended that we keep a record of the time the child spends with his biological mother.
The separation agreement between them 8 years ago stated that she could live in the attached apartment with their child while the child was with her. We pay her bills and keep this roof over her head. She receives a child tax benefit for her child. We do not pay her money as the agreement states her living expenses are taken care of. She does work fulltime at minimum wage. Her money is her own.
All of her child's needs are met by us, ie: clothes, groceries, activities, transportation. She does not have a drivers licence so therefore cannot and does not cater to a teen. Since January, he has spent 29 days visiting her and her family. Most of that time he spent with his paternal grandparents as she was not home although they do live in the same house we are counting that time as time spent with her. It is now October and we will continue to record visitation for a full year as the lawyer suggested.
I'm not sure how to get the ball rolling. When we contacted the lawyer in December he stated there was nothing in the agreement stating we pay all her bills, that are still in my fiancees grandparents names. She kicked up when it was mentioned to her and argued that if she had to pay anything to stay there she wanted extensive renovations done.
Do we have any rights here? Can child support or support for her be a factor when she does not have the child?

Newfoundland is not a U.S. state.

If your husband wants child support, he can petition a court to grant him child support.

If your husband's parents are content to let his ex- live with them, at least to the point that they're not going to take any action to get her out of their home, then that's the way things will continue to be.

If your husband wants child support he should consult a lawyer in Canada. If his parents wish to evict his ex, they should consult a lawyer in Canada. This is a U.S. forum, so there's really not much we can say.