Forced Transaction Code in Parent Portal When Paying

So we need an option to force parents to choose one of our transaction codes when they go to pay for something. Currently, we have to look at every child in the system, review transactions for things they pay for in advance, which happens a lot, and try to figure out where to move money. For us, if a parent pays for tuition that isn't due, that payment gets logged as an empty slot when we view transaction codes. We encourage as much as we can to put in notes, but that's unreliable. If there was a way to force an input of a transaction code, or to have that as an option, when parents go to pay, it would solve our only issue with DSP. How feasible would it be to at least have the option for studios to have that available?