Frustrated w my kids sleeping problems!

My 10mth old usually naps 2x a day, sometimes 3. His bedtime is always at 8pm, but idk why this time he always wakes up at 9pm, and stays up til 11pm or 12am. He wakes up like as if it was only his nap! I was thinking that maybe he needed to nap 3x a day, in order for him to sleep thruout his bedtime. I nap him for 3x, the 1st time worked, but the 2nd time didnt. Whats wrong w his sleeptime? Im also doing a bedtime routine, but hes still waking up all the time like as its only his nap time. Sometimes wed all go sleep over at my parents place, and he sleeps so well over there! He doesnt wake up, even when taking only 2 naps a day! Whats the problem here!? Its driving me NUTS! He also always wakes up my 2yr old, which drives me more nuts!