I usually either cheat and add the trait heavy sleeper or make the baby/toddler’s sleeping need low so they just fall asleep.
Hi,
I have had this problem myself, and it is almost impossible to tend the toddler/baby with the whole family crowding the crib. And often the toddler's sleep pattern is out of sync with the rest of the family. Leaving the baby/toddler un attended is not good parenting, and leaving the toddler outside is not feasible if you have seasons. These are solutions I have done in the past.
A, Lock the nursery door and set to admit one adult sim. This will give your chosen adult room to tend to the toddler's need. This will also stop another sim taking the toddler/baby out of the crib the moment you put it to bed.
B, If I have not done A, I use 'Testingcheatsenabled True' cheat. With this cheat you can teleport the toddler to another room and have an adult tend to its need, or teleport the unwanted adults out of the nursery but for one adult then tend to the toddlers needs, or you can click on the green bar of the needs and slide the mouse to replenish them.
Having given my solutions I think it useful now to give my advice. Before putting your toddler to sleep for the night make sure it is potty chaired, fed and changed, and don't let your toddler get over tired. If you need to have baby sitters make sure the toddler/baby is out of the nursery and lock its door before going to work.
