[NTG-context] [NTG-conte​xt] How to retreive the bibentry number and use it somewhere?

Hi, I sorted the reference by the squence they appear in the text. I want to retreive a bibentry number, but use it at other places. I try to use \onlinecite, this number is the same as \cite[xxx]. Its number will become smaller if I put it before where I cite it. Can I get the absolute number of the bibentry, which means, this number will not change when I use it somewhere?