We co sleep with our children when they were 4-5 mths. We had to buy another mattress for my hub to sleep below so he can sleep better.
My children definitely sleep better when co sleep coz they feel secure n is easier to latch them. My boy slept through at 4 mths old while my gal slept through only at 14 mths. It will be tough if all sleep in queen size bed. Do consider changing to king size or add another mattress.
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