Adelyn's very cute, though I kinda prefer other spellings of it (Adeline). Either way, though, I think it's lovely. Possibly a little too close to Adrian, though? Sienna's not really my style. Makes me think of the color, burnt sienna is pretty popular for paints or pencils, or crayon, even. I can see that being some teasing potential for a kid, but...color names in general aren't eally too bad. But I think it fits well with your other names, the style of it matches...
I prefer Madelyn to Adelyn-it just looks more complete to me. Still it's a cute combo just not really my style.
I love the Sienna Adelyn....very cute! I think it sounds awesome with your boys names!
Heeeyy, you're back! :) No more Giselle?
I like Adelyn... prefer Adeline, but Adelyn is nice, too. I'm not a huge Sienna fan, though--I just think of the vehicle, and this ugly reddish brown paint stuff, haha, and it doesn't even sound that cute to me. I know I'm in the minority because a lot of people love it, but it's not for me. I think Sienna could work with your boys, but I think I like some of your older options, like Juliet, Violet, Giselle, Charlotte, etc., with your boys more.