Cherub Mamma made a good point a while back about the question of what age ranges to take in as a foster parent when she said that someone's birth order is going to get messed with no matter what. (Unless you don't have any kids in your home at all, I suppose.)
I've thought about that because we have always had that as our general guideline for placement ages. "Younger than our youngest", however old he may be. For me, it wasn't so much about not wanting to go "out of birth order" as about not wanting to foster an age I hadn't parented. Although I know that foster-parenting a child can be (and usually is) wildly different than parenting a child you've raised since birth, I still have this sense that I would have no idea what to do with children older than the ones I bore. I wouldn't know what was "normal" behavior and what were red flags. There were so many times with the preschoolers we had here where I had to keep insisting that their behavior was not "normal" in order to get help for them; if I'd never had a child that age, I don't think I would have been so certain that I was seeing things that go beyond "normal." So, that would put us at "younger than our oldest." Our three birth children are less than 5 years apart, however, so mixing in ages older than the youngest but younger than the oldest has a high likelihood of making artificial "twins."Especially when you throw in the details that Edmund (the youngest) is a year ahead in school -- so the school year gaps between the Originals are all the same (They're currently in 5th, 7th and 9th grade.) -- and that Susan (middle) is on the autism spectrum and therefore sometimes behaves as "younger" than her chronological age.
Our first long-term placement was L & O and worked out that way. L was almost exactly 1 year older than Edmund. However, they were both in the 2nd grade during the school year that she was here. It was a disaster. L was not comfortable not being the "oldest"; she was used to being "in charge." She could handle not being in charge of the kids who were clearly older than she was, but she expected, maybe even needed, Edmund to bow to her authority. He wasn't having it. He knew she was "older", but they were in the same grade, so he saw her as "equal." They butted heads all year. Our take-away from that experience was that having two kids so close together didn't work well for us.
I also found, working with L and later with D, that I have much more patience with a frustrated, out of control child if they are preschool age or younger. I don't cope well with an elementary school age child manipulating me. Even though I know, intellectually, that it's really no different than the 3 year old manipulating me. Somehow, on some level, I have trouble letting go of the idea that someone is "too old" to behave in certain ways. Not fair to a traumatized child for me to take that out on them!
So, "younger than our youngest." M, at not-quite-a-year, is certainly younger than Edmund!
Of the Originals, Edmund's spot in the birth order has fluctuated the most. He spent 6 years as the youngest. R & A came briefly and Edmund was 3rd of 5 for that day, but it felt more like a play-date than a placement. Then they were gone and he was youngest of 3 again. L & O came and he was 4th of 5, but also kind of "tied-for-third." (I think it was really the uncertainty of their places that made that so hard.) Then it was back to youngest of three briefly before S & D came. He was 3rd of 5 for the couple of weeks D was here, then 3rd of 4 for a long time. Summer before he went to 4th grade, she was gone and he was the youngest again for several months. Then N came and he was 3rd of 4 again, with a bigger gap than ever. When N left, he was back to the youngest. Then M came and he's 3rd of 4 again and will be for the foreseeable future. Whew! Quite a whirlwind! One of the first things he said when we told him would be adopting M is that he was excited about it because he likes being a big brother.
So, where do I ultimately come down on the "out of birth order" question? Solidly in the middle. I think this is one of the many parenting decisions where it really comes down to knowing yourself and knowing your kids and making the best decision for you. For us, only taking placements younger than our youngest was the ideal arrangement. If we were different people with different kids? A different decision might be the right one. I know a young foster couple that has no birth children and yet has fostered teens successfully. They worked extensively in youth programs before fostering and were very comfortable working with traumatized teenagers, in spite of having no personal experience "parenting"; the husband told me he didn't think he could handle working with kids who couldn't verbalize their wants and needs, so preschool and younger were off the table for them. They knew their strengths and weaknesses and set their guidelines accordingly. So did we. Ultimately, that's what I think all foster parents should do. Be honest with yourselves and your caseworker about what you do well and what you don't; know your limits -- but don't be afraid to push yourself; remember that what works for others may or may not work for you.