before you do anything, you need to have the bootloader unlocked, downgraded to froyo 2.2, rooted and then have CWM recovery installed-from CWM you can flash alternate ROMS and the low space fix. I don;t know if those old methods like unrevoked forever still work. even on the incredibleforum where it originated says it;s been depreciated. HTC did issue some updates that may have rendered them obsolete. since you say you are already on 2.34, it seems like your phones are updated past the point where those methods would work
all the info you need should be in this thread. it;s an involved process but it is worth doing. i looked for an easy 1 click way to root my phones(i have 3) but there was none.
http://forum.xda-developers.com/showthread.php?t=1600904
i did it on a windows xp pc which required some drivers to be installed.
by the way, the easiest way to clear up the low space issue is to delete any excess text messages. more than likely, your daughter saves every text message conversation she has ever gotten or sent. that;s one app that whose data grows over time. another is to move whatever apps that can be to sdcard. of course these are very temporary solutions that have limited lifespan. worse case scenario, you will pass the threshold where your phone can recover free space and become non functional requiring your phone to need a factory reset anyway.