Whenever I take a break, I don't see much weight gain, if any at all, but I lose definition and tightness (ie: I get softer -- A LOT softer) so my body starts to look different. I've never been as conscientious or focused on keeping active in other ways on my breaks as you seem to be, so I can't say if I had made more of an effort to do other things, definition and tautness may have remained.
If weight gain is the thing you're more/most concerned about, I don't think you need to be. As long as you eat healthfully and don't OVEReat, I don't think you'll notice the numbers creeping up on the scale, especially if you're going to be running around with kids on the daily.
PS As Demeris stated, I didn't/don't lose muscle mass on my breaks. All it takes is several weeks of getting back in the "swing of things" (even just starting out SUPER slowly) for everything to start popping and looking more defined so I know my muscles stuck around. If you're going to be engaging in sports activities, I'm not sure you won't keep your current definition/shape. Though, the level of activity and exercise routine you've been maintaining up until the break may dictate your results more than anything else.