First of all welcome to BYC, I do have a bit of info on your question, I have 19 Barred Rock chicks that were about 4 to 5 weeks old at Easter, my grandson went to the feed store with me on Good Friday and saw the rabbits, after much pestering me about a rabbit, i naturally gave in like any good paw paw would, my wife took him to get his rabbit the next day, I do not have a rabbit coop so i just put it with my chicks in the pen, my chicks were just learning to use the 2 x 6 ramp to go back and forth to their raised coop, i was busy tending to my 1 week old chicks, i noticed the little rabbit going up the ramp with the chicks, i go in the pen and look in the coop, the rabbit is setting in the trough of the chicken feeder eating chick starter, that was about 4 weeks ago, now it thinks it is a chicken, it chases the chicks and they chase it, they coop,eat and play together, as far as i know he hasn't tried to roost with them,lol
I would have to say that if they both are the same age and size and grew up together, it might work out ok, i personally wont be doing it, i don't think any way, but between grand kids and maw maw, paw paw may not have a say in the matter!!!!!!!