Rabbits! Indoor /Outdoor?

My step-son has a pet rabbit at his mums house which has been trained to live indoors. His mum has recently told him she might sell it because her new boyfriend has a dog and the dog and rabbit don't get on! I told my step-son that if his mum mentions it again to tell her that we will take his rabbit so he can... show more My step-son has a pet rabbit at his mums house which has been trained to live indoors. His mum has recently told him she might sell it because her new boyfriend has a dog and the dog and rabbit don't get on! I told my step-son that if his mum mentions it again to tell her that we will take his rabbit so he can keep it at our house instead. We already have two cats but they are extremely sweet and tame and we don't see it being a huge problem as long as they are introduced carefully and never left alone without us watching.
The question I have is that his rabbit currently lives indoors, but our house is tiny and we would struggle for room. Can a rabbit that has already been trained to live indoors then live outdoors or would it be too much of a shock to its system? If needs be we would have to find somewhere indoors but it would be a struggle. Does anyone know? xx
Update: Thankyou so much to everyone who has answered my question... it has put my mind at ease! I am now determined that should his mum say the rabbit goes, the rabbit comes here! :) As far as our cats are concerned, I am not too worried,. We have two extremely soft puddies. Timon is tiny and so causes no threat to a... show more Thankyou so much to everyone who has answered my question... it has put my mind at ease! I am now determined that should his mum say the rabbit goes, the rabbit comes here! :)

As far as our cats are concerned, I am not too worried,. We have two extremely soft puddies. Timon is tiny and so causes no threat to a rabbit, and pumba is just too lazy. They are almost 2 years old and so far we have never had an 'unwanted gift'! They often go to see the rabbit that lives across from us when it is in its run and they just lie next to the cage and watch each other!
Update 2: As far as where to keep him, we do have a garage so it would be possible I guess to clear out lots of space and put him a cage in there. I live in the UK so through summer it will be okay for him to be outdoors through the day. Believe me he will get bags of attention which according to my step-son is something he... show more As far as where to keep him, we do have a garage so it would be possible I guess to clear out lots of space and put him a cage in there. I live in the UK so through summer it will be okay for him to be outdoors through the day. Believe me he will get bags of attention which according to my step-son is something he doesn't currently get! We'll spend extensive time with him ( I adore all animals) and we'll often (prob every night) bring him indoors to play! He'll never go without any love and attention :) I can't bear for my step-son to lose his rabbit and I will do everything in my power to ensure that he stays in his possession.

Thanks again to everyone who has answered. xxxx
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