I want to get custody of my niece and nephew even though I live in another state,...possible?

Yes it is possible that you could get the children for long term placement if DHS intervenes and removes the children permanently from the father's care. You probably won't be considered for interim foster caregivers because DHS will want to work with the biological parent or parents to get them to change whatever is wrong so the children can return to live with them. DHS will want to keep the children close where the parent or parent's live so the parents can visit the children as the case progresses. For long term placement, DHS has a mandate to place the children with family members before they are put up for adoption. So you could certainly be considered for long term placement since you are family members and you are raising their siblings. That said, the journey through a juvenile court case is a long and twisted and sometimes illogical process. Most of the players are paid state workers, like the DHS social workers, the District Attorney. The parents may even have court appointed attorneys. You on the other had will have to pay a private attorney out of your own pocket. Because of the long convoluted process and the many parties involved, your attorney fee bill can sky rocket. However you may have not choice if you want to stay informed and be considered for long term placement. You need to intervene early on and remain involved. You will need an attorney to help you do this. The much better solution is for the father to concede that he can't care for the children and for the mother and father to voluntarily consign the children to your care now, before DHS has to take any action. There won't be the need for a juvenile court proceeding if the children are removed from the unsafe environment.

I agree with the above answer. I would add that you may want to identify yourself to DHS as a family resource. Depending on what the plans for these children are (return to parent, adoption, etc) you may be a resource in some capacity down the line.

An Oregon juvenile court will probably not place children out of state. The only way to try for this is to file a motion to intervene in the juvenile court, if a dependency case is filed by the state (it sounds like that might happen but hasn't happened yet. You can't do anything to push it along - private persons can't file juvenile cases). You would have to persuade the children's attorney and DHS that placement with you really was best - but given that these professionals would probably not be able to travel to inspect your home, across the country, or observe your family dynamic, I imagine that could be quite difficult. Oregon law makes it possible for a non-biological-parent to sue a child's biological parents for custody of that child in circuit (rather than juvenile) court. However, Federal law and the U.S. Constitution makes this kind of suit extremely hard. To prevail, the non-parent must plead, and show, that (a) they have developed a long-standing parent-like relationship with the child, and (b) the child would be at imminent risk of serious physical, mental, or psychological harm if left in the custody of the biological parent. The law presumes that parents act in the best interests of their children; the non-parent must rebut (disprove) that presumption by clear and convincing evidence. This is a very, very hard standard to meet. I won a suit like this a few years ago, representing a grandparent who sought custody of her two granddaughters. In that case, both of the children's biological parents were long-term meth users; one had been accused of sexually abusing the children, too. That gives you some idea of the kind of "risk of serious harm" we're talking about. Based just on the information you've provided here, you /might/ be able to prove point (b) above, but you can't prove (a). You haven't indicated that you actually have been raising these children as if they're your own - having them live with you; meeting their needs on a daily basis. So I don't think you're going to be winning custody of them under this law.