Hi, can I just say a couple of things and it may not help you.
Firstly as said you have a good arrangement and please let me say be thankful that you are seeing your kids as much as you are, I had a
Consent Order and it has slowly been eroded over the years, to the point, i now dont see my kids and there is not a lot I can do about it.
Definite parent alienation, my ex always hides behind the 'its nothing to do with me, I try to get them to come' phrase when in reality, i know she fuels hostility and creates situations where my kids are biased.
They are becoming teenagers and like yours, their voices will be heard through court.
Your ex will know this and will start actions to make sure that they say what she wants them to say, so make no mistake you will not gain.
I know and feel your pain in missing your kids, but in this instance, go with the flow and your kids will vote with their feet certainly over the next few years, but they are becoming teenagers, they will not want to be around either of you much, they will want to be where has the best internet connection, the least hassle, the most amount of food they need, no more.