The first task is to make sure your feral has been checked over by a vet, de-wormed, vaccinated and if necessary sterilised.
It may not be a good idea to introduce them into houses with other pets. Though other pets cats may help in their socialising, if you have a bad personality clash you may have to choose between them. This is unfair on the feral cat, especially since they often may bond with a first owner but not with a second.
Don't push the agenda, especially with handling. Persist with attempts to stroke and play with them, but back off if they object. They will trust you in their own time if you deal intelligently with their wariness. Your biggest allies in the process are food, patience and faith that there's a great pet behind the fear.