How to add a existing cell into cell library

MS V8i SS5

Hello All,

I have a cell (sourcecell) in a dgn file, the cell has some tag inside. I'd like to use the cell in other files. But I don't know how to add the cell into a cell library. I have tried:

1. Attach the dgn file as cell library or open the cel library file, copy the cell by Ctrl+C/V, in this way, the original cell (sourcecell) will be a nested cell in the new cell.

2. Drop the cell, all the attached tags will gone, cannot create a new cell same as the original cell.

Does anyone know how to add a exsiting cell with tags into cell library, so it can be reused? Otherwise it almost impossible to use existing cells without the cell library. Thanks a lot!