Co-op game like Brothers - A Tale of Two Sons

Trine?

Most action games are combat oriented so I'd recommend point & click adventures (easy ones). They are not co-op games but you can play them that way.

Never Alone(kisima ingitchuna) is an amazing game

ibb & obb? Not much of a story to it though.

You might be tempted

I would suggest the LEGO games, but there is combat in there, so it would probably not really suit you.

There aren't many indeed as they aren't "profitable" to make, atleast on PC. I mean usually games you describe require many mechanics compared to usual run of the mill killing enemies. It's rather sad really.
Interested to see if there are some gems though that have passed the view.

Never Alone // whoops, didn't read till the end :(
Ibb & Obb // might be a bit too hard while progressing through it :(

Shadow Puppeteer could be a game for you.

The Undergarden and Rayman Legends, though The Undergarden has an annoying thing where if you're not the first player you'll "die" and be warped to where the first player is if you fall behind and don't stay on the same screen.

Mortal Kombat X

What about Wyv & Keep?

I recently played The Cave, it's a funny, lighthearted game with a message which you can play co-op. There is some killing but it's done in a very cartoonish/childfriendly way. There's a demo, so you can try it out and see if it's something for you. Beyond: Two Souls (PS3 exclussive) might also interest you if you have a PS3, though it's a bit darker/more serious. It's also a co-op game.

Edit: Telltale's Sam & Max might be something that interests you (not co-op, also has a demo), The Secret of Monkey Island: Special Edition and Monkey Island™ 2 Special Edition: LeChuck’s Revenge™ (also not co-op, some dying but not a lot). These are adventure games with a strong sense of humor that might appeal to your kid more.

I quite enjoyed "Mini Ninjas". Though there's a fair amount of combat, you aren't actually killing things - when you defeat the skeleton minions, they revert to their pre-enchantment forms as woodland animals. The combat might be a bit difficult, but I think that buttonmashing is enough to do pretty well on easy mode, though it is single player, and you might want to help them on boss fights.

I also wholeheartedly agree with the Trine suggestions.

Teddy Floppy Ear. Single player adventure game with puzzles.

Mountain

portal2

the only Co-ops that I know have to much violence for this case so cant be of much help :/

Rayman Legends and Rayman Origins...

Rayman Origins my 4, 7, and 9 year old boys played all the way thru and they would be so excited if we got Legends.

You could have a look at Chariot (http://store.steampowered.com/app/319450/).
It is co-op with a few enemies and the story is not too deep but your daughter might like the idea of running around as a princess with her fiance and it's good to play with a controller.

It´s not coop, but a nice and not too dark Jump and run game: Max: The Curse of Brotherhood

I remember it beeing not to hard gameplay wise.

Edit: maybe some choose your own adventure? Moster loves you it´s mostly very kid friendly, but they should be able to read and maybe you should play it with them ( but i guess you´ll do that anyway) .

Blood Knights

JuJu
i finish the game with my 8years nephew.. he like it.