need advice for milk transition

Paano po ba mag milk transition from ENFAMIL 0-6 to NESTOGEN 1? Ayaw na po dedein kasi ni baby yung enfamil laging may tira pinatry po namin yung Nestogen ayun nagustuhan nya at nauubos na nya and yung poop nya mabaho and color green hehehe btw 5 months na si baby. Feeling ko po nanawa na sya sa lasa ng enfamil eh. please tulong po, first time mommy po ako