Hello, thank you for the question.
One issue is clearly leaping out at me: the order you have from Superior Court of Ontario ought to be varied by the Supreme Court in BC, not by the provincial level court. I'll bet that your judge said that the provincial court didn't have the power to vary a Superior Court order from another province. Yes, the BC provincial level court will certainly recognize that Ontario order, and can make additional orders or deal with the enforcement of the support, but BC provincial court will say that it can't change the Ontario Superior Court order.
You ought to take your papers to court, get a copy of the judge's endorsement to see if the judge wrote down their reasoning for dismissing the application, and see duty counsel or Legal Aid's family clinic if your court has one.
I know you've been told that you're "conflicted out" by more than one duty counsel there, but I'm sure that there has to be someone who can talk to you and confirm what I've told you here. There might be other issues too. I've done my share of duty counsel work, and in this situation you're not looking for context-specific legal advice about your evidence or what you're asking for (it would be a conflict if the dc you have has previously helped your ex) but rather you're looking for procedural information on which level of court you need to be at, and what deficiencies if any existed in your paperwork which did (or might have) contribute to the dismissal of your application. If you put it to dc like that, they should think twice before saying "conflict". If they still do, ask for someone to help you that isn't conflicted out.
Does that make sense? Feel free to reply with question or comment. If I've answered you, I'd appreciate a positive service rating please.