I just booked ADR's for a group of 13 a couple of weeks ago and we leave in a month. The Cm on the phone was pretty specific when we would be seated at different tables. Like Biergarten, they said a table only seats 8 so we would be seperated, but they would try to keep us close together.
When we went with a party of 13, 3 years ago, we ended up all together or super close at every restaurant.
One little word of advise with a such a large group, try to book buffets. I found with a large group it took forever for everyone to order drinks, then wait for them, then order food and wait for it. At least at the buffets, you can start eating whenever you want. With small kids, we find the buffets are easiest.