Adding a drive before to replace the dying one

Hi,
I have a failing drive. It is one of a 12x3TB RAID 6 ARRAY.
I wish to add the new replacement BEFORE replacing the failing one because in such large array everything could happen: 2 other drives could fail while the failing one could remain functional until the end of the replacement process.

Is it possible to add the replacement drive without removing the failing one and instruct open media vault which one will be replaced at the end of the process ?

Hi,
if I add the new one as spare but the previous one has not totally failed and it is still there and alive, will OMV start replacing/mirroring the failing one ?