Are they not liking being wrapped. My boys wriggled out of their wraps from around 2 months so since then I have used sleeping bags. And they work really well. No blankets needed. So they move all around their cot and don't get tangled so they stay asleep.
I still give them a bottle at 6pm then straight into bed. Adam often sleeps for 30 mins then wakes up and chats to himself for up to an hour. But I don't need to go in as he is happy.
During the day I found I had to start to let hem cry instead of keep going in and they only cried for about 10 minutes. Now hardly ever cry, just sleep or chat to themselves.

goodluck