You can change a device as long as it’s like for like and also do so without stopping the loop, but you will have to be able to safe address if needed and potentially back it up. It is not advised to back up without a current download though.
It can be a bit of a mine field but easy systems to use once you get used to them.
If the choice of using a gent certified engineer is there I would say go for that to be safe.
I’ve just seen the date on this but may still be relevant