Hi, just wondering if anyone has any ideas on how to keep my 18 month old from climbing up the ladder into the top bunk of the bunk bed?? we will be moving him into his 3yr old sister's room soon, and they'll be sharing a bunk bed. I realize they are a bit young for that kind of bed, but we really dont' have any other solution... the room is very small. I'm concerned that ds will try to climb up the ladder to be up top... any thoughts? it needs to be accessible for my daughter though.