8 week olds, 17 week olds, and 15 month old? good idea??

[RAWR]

we have 25 chicks 8 and under, 3 17 week old Australorp hens, and we're wanting to add two 15 month old standard cochins to our flock. will they be okay with our flock, like, in the coop with the babies? my mom is getting me a white cochin and i really want to be sure this is a good idea because i dont want my other babies hurt :\\

 

[RAWR]

also, the coop seems alittle over crowded, but we're building another one for our bantams :\\