ready clean and urine testing

hey, i have a question for all yall about urine testing and ready clean. every morning i take prescribed amphetamines and i was wondering if i take ready clean to cover up the thc in my urine, will it also cover up the amphetamines? the reason why i ask is cuz if my parents notice that there arent any amphetamines in my system, they will know something funky is up. i was also wondering if you have to drink the whole $30 bottle in order to cover up the thc? if so, what are some cheaper alternatives?