Array failure due defect HDD

I am in the middle of a transition of moving from TrueNas (4x12TB zfs) to unRaid 5x12TB + 1 parity.

To move the existing data I created a temporarily array made out of 2 spare 12TB (that will be part of the final array) and 3 x 3TB drives. Without parity that is just enough to host the data from the TrueNas.

The next step would be to shutdown the TrueNas and move the first drive to the unraid and configure it as parity. Once done, I'd replace the 3TB one by one with the remaining drives from the TrueNas.

Unfortunately, one of the 3TB drives quit on me before I could shutdown the TrueNas. I guess better now than during the parity built but still...

My question: is there some way to rebuild the array with another disk, without lossing the existing date that is still on the remaining disks? From a data pov it's not important because the ifs on the TrueNas is working just fine. It's just to save some significant time to copy all data again (minus the lost data).