Lilly has a two pole cat tree with a nest bed a high top perch ladder and hidy hole both of the latter see little use but the former a lot. Now recently when she's been running/jumping up to the higher levels I've noticed the tree rocking forward! I'm worried about her and it falling! I cant attach it to the wall with a strap as the landlord is very picky and will hit the roof for the few pictures and clock I have hung never mind securing a cat tree to the wall. So How can I weight it down at the bottom and back so this doesn't happen?