Day time sleep

Se
My twins are 6w 4d old. Until 2 days back, they slept in their cribs all the time. Now my daughter doesn't want to sleep in the crib during the day. She either wants to sleep in my lap or in her snuggle nest. The moment I put her in her crib, she cries. My son still sleeps in his crib. Any idea why she is doing this?