Sonja and Michael turn 2 months old

All three kids had their doctor's appointment at the same time: a 2-month checkup for the twins and a 2-yr checkup for Nikolas:

Sonja:
22" (25-50%), 11lb 10oz (75%)

Michael:
21.5" (10%), 10lb 15oz (25%)

Nikolas:
36.5" (90%), 27lb 2oz (25-50%)

The most important advice that we got from the pediatrician was on sleep training. She told us that the babies should now be ready to sleep 8 hours straight during the night without waking up to eat. She suggested to let them cry for up to 30min before picking them up, then to feed them a bit and put them right back into bed. Repeat until they fall asleep.
I tried this the first night. It was tough to listen to distressed crying, but after a couple of rounds, they both fell asleep and slept for 3 hours. The second and third night were similar, but progressively more tough: they'd finally fall asleep close to midnight after fighting for a couple of hours, and they'd sleep until 3am or even later, wake up for a quick feed and go right back to bed. After the third day it was almost impossible to let them cry, they just wouldn't stop, so we stopped the training as it was. I realized that early luck was probably due to the cold that both babies got from Nikolas that made them lethargic. Now especially Michael refused to fall asleep on his own, although Sonja might still do it as long as her bassinet had the vibration on and she was in the dark and quiet room. I reverted to nursing him to sleep. The training, I believe, had an effect anyway: the babies do seem a bit more comfortable when placed in bed and don't immediately jerk themselves awake when they touch the sheets.

Sonja and Michael both lift their heads although they hate tummy time. The doctor recommended 10min each day, but we are lucky if we make it to 3min. They say their ghhh's and aaaa's and smile consciously at us, Mike more so than Sonja--if fact, he smiles whenever we make eye contact with him and talks back. He makes a great effort to make as many mouth motions as he can to produce sounds, and he practices his vocal cords well too that sometimes he sounds like he is singing, very cute.

Both are done with pacifiers, although I was sure that Sonja would get addicted to them, and they've switched to their thumbs. Michael is quicker getting his thumb into his mouth, and it's usually his left thumb so we suspect that he'll be left-handed.

Michael:

Sonja: