you don't, unfortunately, you share it, it closes, you hit bookmark again and share it again, this is an easy fix perhaps worth throwing on feedback group, though I'm really not sure if diigo corp is paying any attentiong
twine wasn't twine until we pushed for those types of features, the federated comments was a holy war remember? what we need is some traction with diigo ownership, I'm going to ask wolphram who it is as google was silent on the matter