It's not the way they cut the guards that matters - it's the shaping inside the guard that requires them to know the blade type. Ex: Ultima Mirage blades have a smaller toe rake than Wilson Pattern 99's, so they need less room. My Gold Seal Revolution blades need a wider track inside the guard than my traditional Gold Seals.
While I think putting a pair of $40 Rockerz on pond skates is like putting lipstick on a pig, she can say her blades are similar to Mark IV blades. She does need the length of the blade - it should be stamped on the blade itself. When she upgrades the skates, she might be able to use the guards on the new blades.
I wasn't originally so keen on these pricey guards. After mistakenly stepping on the ice four times while wearing them and NOT falling, I'm a fan now! ♥