That sounds like a yarn from Spotlight? I haven't seen or used it, but I did find a couple of listings on eBay so was able to look at a photo of it. Its a fuzzy-eyelash-fleecy type of yarn, hence the need for the 5mm needles. But it is odd for the required tension to be 24sts per 10cm -normally using that size needle, the tension would be fewer stitches.
However, don't worry about what ply it is. I'm in Australia, but never think in terms of ply. I look at the required tension and use a pattern that stipulates that tension.
Most Double Knit (which you probably might think of as 8ply) patterns have a tension of about 22 stitches per 10cm. Peter Pan DK baby patterns require 24 stitches. You'll probably have to do a bit of searching for a pattern with the tension needed, which would also look good knitted in that yarn.
Alternatively, could you use a plain Double Knit yarn for the main part of a baby garment and the Bella Baby Parade for the bands, cuffs, collar? A matching beanie in plain double knit, with Bella Baby turned back brim?