The boots have gotten small over the years (or maybe her feet have grown)
It is well known that pregnancy tends to change the size and shape of your feet. In particular, they tend to swell up, and stay somewhat swelled. This is perfectly normal - make sure she knows it doesn't necesarally mean she isn't still in good physical condition.
Have you tried removing the insoles to make more space, and maybe have a good skate tech stretch them? That might help, but may not be enough.
Note that TaBalie in this thread
http://skating.zachariahs.com/skatingforums-onice/www.skatingforums.com/showthread125b-2.htmlsaid the old boots are not heat moldable - but almost any leather skates can be heat molded to some extent at about 175 - 180 degrees Fahrenheit. Heat molding may help too - but has it's limits, especially near the bottom of the boot.
On the Silver Star boots, you don't need a fancy commercial "heel insert". Just put a little tape under the insole in the heels to make it snug. If that isn't enough, let the tape come up a little around the outside of the foot (fold the tape over so it doesn't stick), to make a nice tight fit.
Based on what I've seen, people returning to skating after many years often need a few days or weeks before they feel confident. So she may not really need stiffer boots, unless the old ones are broken down.
OTOH, if you can afford it, maybe new boots, and blades, will make her happier. Many ladies love to shop. She can pass on the old boots, and the Double Star blades, to a worthy student... While you are at it, maybe she "needs" an updated outfit, with a professional looking black PSA jacket and pants, or a pretty skating dress.
I encourage you to follow what other people say, and go to a good fitter. They make a huge difference, and are well worth the extra drive. And it will make her feel more special.
If she gets cold feet or toes, one big advantage of new boots would be that she could get a nice warm plush liner, possibly plush ski socks (she wants to be a coach, and will stand still a lot), and leave space to replace the insoles with closed cell carpet foam cut to the same size and shape. Closed cell carpet foam is several times better insulated than most insole material, and if you cut it yourself, you can create a perfect fit.
As a coach, if she still has credentials (which you need to coach almost anywhere), she can probably get a discount on her boots, and maybe on her blades. Contact the boot and blade companies to see.