There's no reason those books can't be in the EYB Library if they have recipes, but if you add them using the Import Books function, they are likely to come up in our system as "wrong category" and therefore not be added automatically. There have been issues in the past of some members importing a huge list of ISBNs for their entire book collection regardless of whether or not the books contain recipes, so anything not coming up as a cookbook specifically now has to be approved.
It is highly unlikely these types of books would be popular enough to qualify for professional indexing, but could always be member-indexed. In fact, if there are just a small number of recipes, they might be good ones to try your hand at member-indexing and get a feel for it. One of my son's picture book treasuries had a few recipes in it and I member-indexed it last year. It's nice to have them on your Bookshelf and can be a much lower time committment than a "real" cookbook. Send us an email at [email protected] (or using the "contact" link anywhere on the site) if you want to member-index any of these titles and we'll make sure to get them added for you.