Props placement in quays

Hi everyone, trying out CS2 since it’s been free to play (last day today so making the most out of it) and I have a question about props:

• was placing some quays and then wanted to plop some benches facing the sea on top of the quays but it doesn’t let me “overlap”. Is there a way to place props on quays?
• also, is there a way to overlap props, for example at the end of the quays I’d like to place a bunch of boulders to make it look like the quays end at some random rocky formation, but same issue, can’t seem to overlap?