Firstly best to post about health or behavioural probs in the proper section..just so you get more advice.
How old are you benglys and whats the neutered status ?
Clean the areas with washing powder / water..leave to dry then you can spray with surgical spirit. Also highly recommended is the "simple solution" you can buy online, its pretty good (someone correct me if i have that name wrong)
and i'd strongly recommend you buy some "feliway SPRAY" and use that in the area..its works really quite well. You should maybe think about getting a couple of the feliway plug in diffusers to put on aswell..remembering to unplug any normal airfreshner ones so the perfume doesnt mask the feliway.
some people advise putting a bowl of food down where they have pee'd as they shouldnt want to eat where they toilet, other suggestions are cover the area with an object or tin foil. have they got adequate litter tray provisions, have you changed their litter type ?
Linda's tribe are very clean and well behaved but i have an aunt who has 4 or 5 benglys and 2 of them esp (un neutered females) are really dirty choosing to pee and poo in the house and furniture regardless of what she's tried, one of their kittens also had same traits...so i cant say if its something common in bengals or perhaps my aunts problem more due to them being un neutered.
Hope you get it sorted out, if they are young then maybe they need to be neutered early ?