FeLV for these 2 indoor cats with their vaccinated outdoor roommate?

We have 1 indoor/outdoor cat and 2 indoor *only* cats. The one that goes outdoor gets the full panel of vaccinations ie Rabies, FVRCP and FeLeuk. The other 2 get all but the FeLeuk. But I do wonder if the 2 indoor kitties should also get FeLV. I am not concerned that they will escape into the great outdoors (this is very unlikely). And so I think the only scenario by which they would contract this terrible disease is that our outdoor cat be bitten by an infected feline AND our cat's vaccine FAIL....this is the only way? 

What is the prevailing thought re. this vaccination under these circumstances?

Felv is a little more contagious Than just bite wounds. It can be passed by close contact (sharing bowls, Mutual grooming) and can be passed through feces/urine as well. Your outdoor cat is more at risk because they tend to fight with other cats for territory. But if the vaccine fails with your indoor/outdoor kitty, your other two are at a bit more risk than just being bitten by him. Unless in the rare case another kitty gets in your house- I've heard of that happening with some cat doors? Really rare though. It's a long shot, and vaccines do fail, if it were me I'd rather be safe than sorry.

Feralhound said:

Felv is a little more contagious Than just bite wounds. It can be passed by close contact (sharing bowls, Mutual grooming) and can be passed through feces/urine as well. Your outdoor cat is more at risk because they tend to fight with other cats for territory. But if the vaccine fails with your indoor/outdoor kitty, your other two are at a bit more risk than just being bitten by him. Unless in the rare case another kitty gets in your house- I've heard of that happening with some cat doors? Really rare though. It's a long shot, and vaccines do fail, if it were me I'd rather be safe than sorry.

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I agree with this.  Maybe this article will give you more information:  http://www.thecatsite.com/a/feline-leukemia-virus-felv

UPDATE:

We brought her in earlier this week and she was administered the first of the two FeLV shots with the second to occur a month later.

(Looking at her records we now realize that the breeder omitted the FeLV shots when she was a kitten and so he she has not had these shots at all until now...she is 18 months old).