OK, I skimmed this thread and... eh. Honestly I'm on my third Sunday afternoon beer as I sit here on CR procrastinating calling the cable company to complain about my rates being too high and the inevitable fight over a better deal. But I know everyone on CR is anxiously awaiting my input on this so I guess I'll toss in my 2c...
IMHO - I like the OP's style and I think his posts are cool. He and his wife are very blessed to have a happy healthy and quick toddler to photograph. I think the 7D-II will be a perfect camera to shoot the little guy (?) with to get him in action shots. Also, the choices of lens will work great. However, in my experience with crop vs. FF, the wider the better. At least that's usually my journalistic style. So go ahead and pick up the 16-35 ASAP. I agree with the other poster that on a crop sensor, the 16-35 will be more "normal" and useful.
But it sounds like you (the OP) are going to buy the 5D Mark IV pretty soon anyway after it comes out based on reading between the lines in your posts. FF is really what you want. And that's great! That way, both mom and dad will have their own camera to shoot with and hopefully the busy toddler won't have to suffer through a trial separation due to the fighting over who gets to use which body! Because I own the 7D-II and the 5D3 and they are both superb. The 5D-IV will more than likely be another stellar 5D body once Canon irons out the inevitable kinks in the first year.
Now if I haven't baited this thread enough, let me know but I figure this will be good for at least another 5 - 10 posts in response and the OP likely can't resist either! Bwahh Ha Ha Haaa!