Hogwash to the entire "written consent" and discussing this with your stepdaughter's bio mom. That's not your job, that's your husband's job - I don't think you raising meat birds and encouraging them to be a part of the process is anything that could be used against you. If you force them to be, that's another story. I assume that your husband is an active parent, and has a say in their lives, so if he's on board, and you're not overbearing and forcing the issue, the knowledge they will gain from the process is invaluable. I say start with Food Inc. and begin discussing as a family where food comes from, how its made, etc. Start teaching them now, and prepping them for later. I also suggest laying birds first, get day old chicks and then get a couple of pullets so they don't have to wait 20 weeks to see the fruits of their labor. As you're doing this process working them up to having meat birds around might be a bit easier.
When the decision to have meaties is made, then you'll need to discuss the process of slaughtering them and what to expect. They may (or may not) want to be a part of it, let them decide. I think it would be far more traumatic to force them to watch, so if it is participation or watching by choice - I think that's fine. Your entire family may like it, and next year you might raise more, and your girls may want to be involved. Kudos to you for stepping up as the stepmom and trying to impart some widsom. Blended family raising isn't easy, I know because my son's father probably watches from a distance what we are doing to raise our son with my husband. But, he trusts us and our parenting style. That is key. Best of luck!
I have a 4 yo, and wonder the same thing, is it appropriate for him to see us process the chickens? I don't know what the right age is, but I know the longer I wait the more traumatic I think it will be. He knows our meaties are dinner, we've told him that from the beginning. We are also raising pigs, and have egg birds, so he's getting the full experience in raising animals for food.
Thanks to another family in his day care, their son told mine how they get slaughtered. His parents did a better job than I would have ever done trying to explain it to my son. Essentially it goes a little something like:
First you put them upside down in the cone and then let out all of the blood until they don't move anymore. Then you put them in hot hot water so the feathers will come out. Then you pull the feathers off, and then you reach in side and take out the insides.
I have to admit that I'm a little nervous about processing the birds, but as I read, look at images, and prepare myself, I have an easier time with what I'll be doing in 7 weeks (and counting). If you asked me 2 years ago if I'd have 17 laying birds, 2 pigs and 25 meaties, I would have said you were nuts! I like knowing where my food comes from. My husband refuses to listen to my ramblings, he'd rather not think about it. Its better to know, and make the choice to eat that food, or to raise your own.