Seems like a perfectly reasonable request. Even as a member of a ward and the father of my children it is often very hard to get information about them. I'm sorry, but relying in the ward to just nicely include you isn't going to cut it every time. And here's what I mean.
I am the father of all girls, I have no sons - this means, culturally, that nobody communicates with me about anything related to my daughters. I have dealt with this in 4 different wards and it was always the same. I'd ask to be included on announcement texts/emails, etc.. and I'd get them for a few weeks/months, but inevitably the 'list' is created again by someone, or my daughters move classes and I have to go through it all over again. I was constantly dropped from communication even though I had 4 girls, I'd explicitly asked the YW Presidency, asked advisers, etc...
There is no reason that a father can't be included in that kind of communication, One never knows... Imagine of the issue is that the mom doesn't want it because she's using the issue of him not getting their kids to church events against him in the divorce (as easily a possibility as the father having some kind of ulterior motive).
Now, I don't understand the dynamics of that family and it doesn't sound like the person withe the question does either, so I'd error on the side of just being good citizens to parents and add them. That, or have the Bishop get all up in the family business, invite them in to a meeting together and figure out what the issue is.
Never underestimate how bad our church members communicate with each other, especially leaders - it is the absolute worst thing we do in my observation. Sure if you're on the Ward Council, if you're on the Stake Council, other than that it's hit or miss about which leader decides to communicate to which members which way and in what amount of lead-time. Of course if we just used all the online tools the church has provided, there would be very little need for anything else, but every org, every class in the church chooses it's own way to send information to parents, youth, and general members, it is the largest mess I've ever seen organizationally.
“A long habit of not thinking a thing wrong, gives it a superficial appearance of being right, and raises at first a formidable outcry in defense of custom.”
― Thomas Paine, Common Sense