young adult / parent's property

[nightcat]

I am puzzled and need a legal eagle to explain something to me.
Where I grew up it was totally normal that when a child became adult s/he was by default a co-owner of the property s/he was living in with the parents and if the parents died s/he was neither forced to sell it nor pay any inheritance taxes, after all it was his/hers residence.
Here it seems to be different and as my ds is in late teens and disabled, I would hate for him to become homeless if something happened to us.
So, how can one make a young adult a co-owner of the house to ensure that he can stay in it (as it's beed adapted). I think he would probably be able to live alone with some help, but I would hate for him to be turned out of his own home and he definitely wouldn't be able to handle the sale, move, adaptations etc.
Does anyone have any advice?

1. Make a will
2. Take the advice of a trust/tax specialist to see how /if the property can go in to a trust to reduce or extinguish inheritance tax. There might be special provisions where the beneficiary is disabled, but I'm just making a wild guess here. Proper professional advice is essential.

thank you Collaborate, I am gathering my thoughts how best to approach it before I go to see the experts