I'm not experienced in hair meshing (I'm currently in the process of finishing my first succesful custom mesh) so unfortunately I can't fix it for you, but I think I know what the problem is. First - all toddler hair recolour files are missing the SHAPE thingie in their 3D ID referring file thingie
That, I could have fixed, but there are also only two 'Material Definition' while all the other ages have three and I don't know how to create the missing file, or more specifically - what long, funky number to give it...
So, yeah... Sorry to be rather unhelpful...