read this and be amazed:
http://www.communitychickens.com/magnificent-mothers/
... and here is my own brief experience/experiment:
i have two silkies, dodo & ditto, who became broody at the same twice. the first time they raised their chicks together without much animosity. the second time around, both again became broody within a day apart but this time ditto abandoned her eggs - possibly because i was handling her a lot. she had been sneezing for quite a while and i had to force-feed her antibiotics. (broody hens, as you probably know, hardly eat or drink - so, unfortunately, there was no other way to get the appropriate dose into her.)
for reasons i can only assume, the hatch was not very successful and only 3 chicks hatched. this made me contemplate getting an incubator - but i am also very aware of the multiple benefits for chicks to be raised by a hen. (the level of emotional [sic!] comfort makes me actually pity all those chicks who are left to themselves resp. an electric brooder.)
for this reason, i, too, pondered the question if a non-broody hen would actually accept newly hatched chicks and once the youngest chick was 5 days old, i decided to test ditto who, by then, had been off any eggs for about 3 weeks, living with her flock and roaming freely during the day.
i set up a pen outdoors and moved dodo and her chicks into it. once ditto spotted her, she engaged her in a fierce battle through the fence. no other hen showed much interest in these newcomers let alone such intense 'feelings'.
i immediately removed dodo to put her back indoors and hence out of sight - but i decided to exposed her 3 chicks to ditto and placed her inside the pen where the chicks were left behind. i only did this for 2 maybe 3 minutes. obviously i wanted to keep this 'experiment' very short.
although ditto had been in a heightened state just moments earlier, she did not attack the chicks and showed no signs of aggression. instead she seemed to alternate between a "keep calm and carry on"-type of attitude (casually pecking at the grass around her) and studying the chicks (no pecking, just peeking). while i would not have wanted to 'test-drive' any of my other hens, i am pretty sure that the little silkie would have adopted the chicks in no time.
my conclusion is that the benefits of finding a surrogate mother for your hatchlings outweigh the risks by far. obviously, you would want to try a bantam breed (such as a silkie or cochin) known to be especially predisposed to 'motherhood' (and less likely cause a fatal injury with just one peck). you will want to further expose the chicks only in a calm environment that you can fully control (such as a small pen) and in which you are able intervene and catch the hen immediately.