So, in my last search, I found this way of doing an X box in one pass.  Will be trying it on my next project.   

I've also been given an old jersey duvet cover to use as the backing.

I've only done a bit of quilting for family and friends, so not a professional.  Someone with more experience may not agree, but I would not think of using jersey for the backing for a quilt made of silk remnants.  That way lies insanity, as the backing would stretch while you're trying to quilt it. 


I would also ask whether this is meant to be in regular use.  Silk and baby messes are not a good match when it comes to cleaning up.  If it's meant only for decorative use, maybe.  It's a lot of work and made more complex if it's a variety of different silk weaves (as your description seems to say). 

I have many old sets of Boye needles.  Mine were purchased in the US.  A size 8 = a 5mm needle and a size 4 is a 3.5 mm, per an old chart.  I've used a size 4 with worsted without difficulty for ribbing.  Larger needles create looser ribbing.  It all depends on what you prefer.  I would try working a swatch of ribbing with your yarn with any size 4/3.5 mm needle you have or can borrow.  That will give you an idea of the gauge of the ribbing and whether it will be comfortable both to wear and to knit.  If you find you prefer a larger needle, just adjust the number of stitches for the ribbing gauge.

Just a thought:  is Lekala an option?  They have a few trouser patterns for boys that might provide a starting point and measurements can be entered for size.

Has anyone tried the Kai Seam Ripper?

Well, I asked that since I had ordered one and now it has arrived.  I tried it on a casing for elastic that needed replacing.  It works but you do have to be careful not to cut fabric.  The elastic casing was wrinkled, of course, so probably more challenging than a flat seam.  I pinned one end to my ironing board to create a "third hand" to be able to stretch the casing flat.  Started an opening with a regular seam ripper large enough to insert the Kai.  It was awkward at first, but with practice, it worked pretty well. 


If you have long flat seams to open in a stable fabric placed on a flat surface, it would be faster than other methods.  Not my first choice for thin fabrics or knits, for sure.  It's basically a razor blade with a plastic frame around the blade to lift the fabric apart as you go.  I wouldn't bother to replace it if lost.

I like that Clover one as well although my favorite was the one that came with my old Bernina.  There's a new "seam remover" from Kai now.  Has anyone tried it?

You won't see it on your posts but on other members, hopefully, below their avatar and moniker.

@Renegade Sewist - I used vegegrow's post as a screen shot.  All I see are broken image icons in place of the thumbs and so on. 

I seem to use everything except weights.  Pins plus rotary cutter for larger pieces - I also like to keep the pattern piece with the fabric until I use it.  Plus, I find it easier to mark darts and dots and such when the pattern is still attached at several points. 
I use pins and scissors for smaller pieces or fiddly cut-outs.  I started using the rotary cutter for patterns soon after I bought it for quilting.  It just seemed to go so much faster than using shears.  Occasionally I'll use a quilting ruler with it for a long straight seam but freehand works quite well once you're used to it.