you could try letting them spend time closely supervised by yourselves. cats are cowards sometimes and if theres only paws when bun is caged..not when bun is out and about and the cat runs off if bun comes up..then its a good sign id say.
my old cats were both 7yrs old and my cat was 6yrs old when we got kibbles..she had one of those cages that had a plastic base with clear plastic sides and a grid lid. but when my two older cats saw her they went up to the cage sniffed fluffed up their tails and leggedit. my cat however went up and introduced herself..they became best pals..the neuter tom was the love of kibbles life even made her have a false pregnancy
tabby however was her nemesis..if kibbles was very ill with her dental probs(she was a dental bun with lots of probs) and tabby hadupset tummy again and was being straved then taby would prowl around her cage and sit on top trying to swat her..no claws tho but i owuldnt trust that sistuation but the rest of the time theyd paly and if they fought..theyd have a quick box like hares an taby would have to run away or kibbles would have beaten her to a pulp!
we lost our tom to heart failure and kibbles pined away she was pts about a month and a bit after he died and the other two cats missed her so much they wouldnt eat for 48 hrs and kept looking for her ubder my bed etc as she ran free in the house in the end!
we got our second bun a uppy eared bun and the cats would swat him as he ran past as he was sooo fast and annoyed them trying to sleep but they were quite close in the end.....when he died suddenly they were uspet then too..tabby was recovering form kidney surgery etc and didnt relasie he was gone for a while. whereas my cat was looking of rhim for a week or more.
we got a mini lop a month or so after and as soon as he arrived he was held down for ehr to sniff..she licked him on the ehad sniffy kissed his nose and her tail wchih had beeb kept donw since woozle died went up int he air and she purred real loud.
both catsd passed away within a few months of each other and our mini lop had ot have a partner as he was sooo lonely without them!
we have two cats now from kittens and theyre two......they grew up thinking bif was their mum and bertie was their dad. when we got our young frenchie they regarded her as baby sister..still do even tho shes massive!!
bandit they get more excited by as hes so hyper and nervous..they liek creeping up on him patting him or nudging him bunny style just to make him jump then walk off laughing..till bif chases them to tell them off but they love their mummy and if she tells them off they get embarressed and sulk.
never ever leave them loose together..but ifoyu ifnd they get on real well they can beleft to play within your sight etc..but best cage up whilst out or overnight.
ours all live as a family very confused family!!
if youre cat is a prolific hunter..my advice is...keep your guard up as those cats cant help killing prey so close at hand. my tow get over excited playing with the buns every now and then but the buns usually tell em to get lost and they do unless its willow she likes to wrestle the cats play chase with them..and peek a boo and even follow my leader...she loves em AND THINKS she is a cat but then we have the cats who thinkt heyre rabbits..very odd!!
keep and eye but what oyu did on your sons lap with the cat and bun side by side is a very good idea to start with. put some pen panels etc or soemthing to stop kitty from pawing thru the bars....or provide bun with safe haven form paws!
then they can get to know each other by scent sight and even being close by each other.
baby buns or tiny breeds are more at risk than medium to large buns...the smalles we have is a lionhead and hes th eone they know they can make jump but they wash him etc and he likes to wash them so its only play.
bif isnt much bigger than bandit really but shes their mum so they listent o her!
play it by ear..spend time togehter on the floor with them. it might work it might not..but a try is the best thing. ive foind each time that the cats and buns are great company for each other i think its the fact that alot of bunny and cat body language is very similar and they will only love oyu if they feel likeit unlike a slavishly devoted dog!