Cats can be perfectly happy indoors!

But try and provide lots of things that can imitate the outside and provide stimulation.

Like:

Cat climbers (big and small)

Shelves for them

Beds/sleepers in different locations around the house

Food in random places for them to find

Water in a couple of places

Food balls

Window sills free so the cats can look outside and watch the world go by

Lots of toys, but remember to switch toys regulary to keep the cats interest, also in different places

Also there are cat tunnels, gyms etc

I am only going by what i did when i my cats were kept in! And by what family/friends do.

But reading your post, your cats seem to have a super life!! Don't feel horrible by keeping them in! You know what is best for your kitties and if keeping them inside is better for them and yourself (peace of mind i mean lol!) then good on you.
xx

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