That's a lot of people, yikes!
I think the main thing is to have everything in one place so you don't have to go back and forth to the kitchen, stepping over babies and parents on the way!
So, have one table set to the side with the cake, food and drinks on, with jugs of water, glasses etc, and plenty of napkins.
Have several rolls of kitchen roll under the table to mop up the inevitable spillages.
If possible, move out out any surplus furniture (tv, coffee table etc) and things on shelves/window sills, so that there is room to people to sit on the floor when you run out of seats, and put drinks/food down (out of baby reach) while they juggle small people.
See if you can put some extra floor cushions/beanbags down.
Make sure people don't stay too long - a couple of hours is plenty!
If you can be arsed, it'll look more 'together' and less chaotic if you can colour theme it - whatever your decor is, go with that rather than a separate party theme as such. So if your living room is neutral with red cushions, get red paper napkins, put some red bunting on the edge of the cake table, red balloons etc etc. and stick with plain/white bowls/plates.
Hope this is helpful, it really is low key I promise, as long as you sit down for half an hour to plan it in full now! Last minute stuff is bloody stressful. :)