To the Original Poster
I am going to stop arguing with Rmet, since Remt doesn't know what she is talking about on this issue. I am also going to give you the same advice that I would have given you offline, so that the others don't get all huffy about "underground" information.
Ok...here goes
Do not obey the order. You still need to make a jurisdictional challenge in Ohio and obeying the order is accepting Ohio's jurisdiction. Ohio definitely did not have jurisdiction despite what the others have said. You are not breaking the law by refusing to obey the order, because it is an invalid order. The grandparent visitation suit is separate from the parental case. States don't have jurisdiction over children, they have jursidiction over court cases involving children. Just because a state may have jurisdiction over one case (an ongoing parental case, which remains in effect until the children are adults) doesn't give that state jurisdiction over another case involving that child.
For example, if CPS in your state got involved with your children due to a neglect or abuse situation, Ohio would not be able to assert jurisdiction over that case either. Its a separate case. Ohio can only assert jurisdiction over the ongoing case between the two parents....and in your case ohio wouldn't be likely to do that because neither of you are residents of Ohio any longer.
You need to get an attorney in Ohio, QUICKLY because you don't have much time. You need to have the attorney file a "Motion to Correct Errors". In that motion the attorney will need to outline the fact that you and your children were not residents of Ohio at the time that grandma's petition was filed and that Ohio did not have "subject matter jurisdiction". You can also include in the motion that the children are teenagers and have no wish to visit with grandma. The judge SHOULD vacate the order. The judge should understand that Ohio doesn't have jursidiction and that its a moot point anyway because the kids are teens and don't want to visit.
However, if the judge stubbornly tries to hold on to jurisdiction (which shouldn't happen but might if the judge wants to teach you a lesson about properly responding to service in a court case) then you have the option of appealing the case, where you would win, or of simply ignoring the Ohio order. The Ohio judge cannot enforce it over the Ohio border. Nor can the police in your area do anything to help grandma. Personally, I would recommend ignoring the Ohio order and reserving your financial resources for any court action in WI. (and one more thing. If you were properly served in WI, then the judge knew full well that Ohio might not have had jurisdiction in the first place)
You want to tell the Ohio attorney that you only want to retain him/her to handle the "motion to correct errors". That you will decide whether or not to retain him/her further based on the results of that motion. You don't want to pay a large retainer to the attorney if you aren't going to handle anything further in Ohio. Plus, if you choose to handle things further in Ohio, you will probably want an attorney that specializes in appeals. If you choose not to handle anything further in Ohio, or to use that attorney for an appeal, then be sure to officially terminate the services of the attorney so that the attorney can no longer accept service on your behalf.
You cannot at any time voluntarily obey the Ohio order, because that would be accepting Ohio's jurisdiction, which again, Ohio does not have unless you make any further mistakes and give it to Ohio. Again, you are not breaking the law in refusing to obey the order....because its not a valid order. However in case the judge gets really ticked off about not being obeyed, you will need to be sure to keep out of Ohio. Grandma may file for contempt in OH...and the judge may find you in contempt but don't stress over it. Even if the judge sentences you to jail for contempt, don't stress over it. Its not a valid order and the judge cannot enforce anything as long as you stay out of Ohio.
At that point grandma would have no choice but to bring the order to WI and to attempt to have it domesticated. If she chooses not to do that, then everything is over (as long as you stay out of Ohio). However if she does pursue it, at that point you would argue against the domestication because Ohio did not have jurisdiction to make the order. The WI judge should agree with you. At that point the judge would either dismiss the domestication case, (and tell grandma she has to start over in WI) or the judge would choose to take jurisdiction and hear the visitation case at that time. Because the children are teenagers and don't wish to visit, the WI judge would have no basis to order visitation. However, just to be safe, you need to include Troxel as part of your argument. Again...its not a parental case and the rules are different.
Should the WI judge decide to domesticate the order after all (which the judge might do because the judge might want to teach you a lesson about properly responding to service in a court case), then you would simply turn around and file a motion to vacate the order, based on the fact that the children are teenagers and do not wish to visit, again you would throw Troxel into that argument too. (USSC case, Troxel vs Granville, June 2000)
Again, the judge should vacate the order. However, if it actually gets to that point, and the judge DOESN'T vacate the order, then you need to appeal. If you appeal, you WILL win.
There is a decent chance that nothing will go beyond your "motion to correct errors" in Ohio....as long as you get on top of that and handle it quickly...like first thing Monday morning. You may have a 10 day deadline for filing that, and you will already be half way through those 10 days on Monday. So get yourself an attorney QUICKLY.
However if your mother is bound and determined to maintain some form of control over you, then its likely that she will bring the case to WI. She knows that the children don't want to visit even if she refuses to admit it.
So this case is about control rather than about the kids. The kids will be 18 soon (some sooner than others) and will have free choice whether or not to visit her. Therefore she could have just been patient and waited...its not as if they were little ones who would completely forget her. Therefore don't be disappointed or stress out too much if she does bring it to WI.
If its about control she still would have brought it to WI even if you hadn't messed up and not stopped it initially in Ohio.
EDIT: No one should ever remotely think that any of this advice or strategy would be applicable to a parent vs parent case, even if there are jurisdictional issues in those cases.