Wanted: / ADVISE / HELP for a loving cat owner in Wahnapitae, Ontario

We love our cats, ALOT!!! We have had animals for 40 years.
We need advise on two of our cats.
Both female, one is 2.5 years old and the other is 1.5 years old.
They have both had kittens this past summer. They are not spayed (we are planning on it but do not know if this would fix this problem).
Since the kittens they are now arch enemies.
They stock each other continuously. They fight, hiss, you name it, they do it.
They pee and poo all over the place (we have 6 litter boxes way more than we need).
They have peed on our couch and love seat and chair in the living room too many times for me to clean it now (we are going to be getting it professionally cleaned and the foam cushions replaced).
They have peed in boxes, hampers, laundry baskets, any clothes or boxes left on the floor.
They have peed on beds.
They have peed on lunch bags, back packs.
They have peed on top of our fridge.
They have peed and pooed on our stove and toaster (not a pretty smell).
They pooed in the kitchen sink.
We keep our house VERY clean and this is a continuous job of clean up after them.
We have tried keeping them separate in different rooms.
We have tried keeping them together in the same room.
We have tried the wall plug in destresser and the drops from the pet store.
We have tried different cat litters.
It is VERY frustrating.
We have replaced many items and purchased many cleaners as well as made our own cleaners.
We have researched everything everywhere possible.
We do have other cats and they get along just fine with each other and the two troubled cats.
We LOVE our creatures and do not know what to do.
They are great cats - just not together.
Any advise / help you might have would be greatly appreciated.
Signed a loving, caring, pet owner who is at the end of her leash.