I have a kids go free ticket and I would like to use it with buy one night get second night free. We are family of two adults and to small kids?

Call customer service

Call customer service usually to purchase hotel separately, you must be an annual pass holder, but perhaps customer service can help. Or try purchasing hotel and buying tickets at the gate. To use coupon for kids must buy tickets at gate and pay full price for adult.

Honestly I would call the Legoland customer service just to be safe :)

U have get coupons for that