Need Clothing Options for Small Sized Boy

Does she buy clothing for him based on his age or size????
If he is petite... then she needs to buy clothes that probably are smaller for his age.
So maybe size 7. Versus size 8 clothes.

Also, buy pants that have adjustable waists. Old Navy and Gymboree and Gap have those. Probably also The Children's Place store. They all have online shops as well.

Or put him in shorts, with adjustable waists. So she does not have to worry about length. Or Bermuda shorts.

Aside from "slim" which varies a great deal in what is considered slim (great option, don't get me wrong, but it's very "try on" and cross your fingers!)...

http://www.bodenusa.com/en-US/Mini-Boden-Clothing.html#nav not only has a different set of sizes, but also has an elastic band sewn into the waist (normal looking waist, but the band gets pulled on the interior as it's sewn into a hollow waist band, and then buttons, making the waistline super flexible)

Altering is another option (costs $5 to have a waistband narrowed at most drycleaners).

As is girls' jeans for a 4th option. Jeans are jeans... but girls jeans have longer legs and narrower waists than boys jeans. Pretty easy to get plain ones. My son's best friend only wore girls' jeans for 5 years, because they fit PERFECT. No one knew, because, they're JEANS. As long as they don't have sparkles or embroidery, who's going to know? HE didn't even know. Because his mom buys them. Then... as soon as he got to a size where he could do the waist/length thing, he was fine. ((It's hard to get over cultural conceptions however. I'm over 6' tall and have a quad D chest. The BEST fit for me are maternity clothes because there's room for the girls, and then the "belly" area is just a couple inches of extra fabric. So for sexy, cute, form fitting tops and dresses... I shop in the pregnancy aisle. I know... backwards, right? I never would have considered it until I started modeling. And I learned the "trick" of how to buy affordable clothes. Gowns are all sized for 6 footers -assuming I guess that normal people get them altered, so gowns are no problem. But PANTS are hard to buy. 36" inseams practically don't exist, and those that do run $150. Owee. But even after YEARS of shopping maternity, just because of the cultural connotation, I have issues with it. So even though girl jeans may fit your friend's son like a dream, she may not be willing to do so.))

My little guy has this porblem, too, but he is still much younger that your nephew. I have found adjustable waist pants at Kohls (Sonoma brand) and Target (Oshkosh). My 11 yr-old niece still wears adjustable waist pants. If they make them for girls, then they must make them for boys, too. They usualy shop at JCPenney.

Gap online and JC Penney (both in store and online) carry slims.

My son has always been skinny. This is the first year he will be wearing "regular" size pants. I cannot remember how tall he was entering 3rd grade (he is 61 inches now, going into 6th) but I believe he wore a size 8/10. I have always been able to get slim pants at Target, JcPenney and Kohl's. For shirts, I just have to let them hang on him a bit when they are a little baggy.

Has she looked at Children's place? They have slim jeans with adjustable waists. Adjustable waists on things like jeans and dress pants - they have built in elastic that you can tighten inside the pant waistline. Lots of places are making the adjustable waist pants now (Old Navy too I think?), but I know Children's Place has SLIM sizes too... so they should help. The shirts, I can't help much. My son is only 6 and I have the same issue - I have to buy pretty wide shirts to get the length my son needs.

Look for Slims that have adjustable elastic waistbands. I just bought Dickies uniform pants for my boys and they had a choose of Slim, Regular, and Husky and they had adjustable elastic waistbands for all sizes. The waistbands have buttons on each side toward the front and the elastic bands have button holes. You can adjust the band to the right snugness. I to have a slim boy and have had to do this. I believe you can also get pants of other brands like this such as The Childrens Place and Old Navy.