OK, this is clearly very important but not an emergency in law and I'll tell you why.
Under rules 14 and 15 of the Ontario Family Court Rules, one of three situations has to be in place before you can get an emergency motion granted. Keep in mind that by bringing an emergency motion you are asking the court to change another person's rights and obligations without notice to them (ie without serving them with your documents and sworn information about the allegations, and giving them an opportunity to reply) which is a big deal in a democracy.
Firstly the children have to be under an immediate risk of serious physical or emotional harm, and I do mean immediate and serious. Based on what you've said, the court would most likely not give you emergency custody if the child welfare authorities haven't deemed it to be an emergency and acted already.
Secondly, there has to be a recent and credible threat that the other parent is going to take the children out of the province contrary to the expressed wishes of the custodial parent. Since you don't have custody as I understand it, this won't apply.
Thirdly, there has to be evidence that the other party can't be located and you can't serve him with your documents, which is clearly not the case here.
Judges hate emergency or "ex parte" motions because they are asked to move children around with only having one side of the story. From what you've told me, I don't see you getting an emergency order.
By all means bring your application for custody and a motion for interim custody returnable as soon as possible. But I don't think you have grounds for an emergency motion. Keep your appointment with duty counsel next week, fill out the forms and get dad served with a copy as soon as possible, and press on from there. Duty counsel will help you as best they can. I always recommend getting a lawyer if you can afford it, but if Legal Aid won't help you then you have to press on yourself or trust the Children's Aid Society to do the right thing. Personally, I rarely trust the CAS to do the right thing.
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