Thanks Maxim.

I did look at BLOCKREPLACE, but it doesn’t seem any help for this; you can’t select blocks from outside the drawing, just make substitutions. This is the only way I can make it work so far;

- Create various blocks in individual .DWG files.

- Insert blocks into desired drawings.

- Edit the original .DWG of each block file to make amendments.

- Go into each drawing file that uses the amended blocks, and re-insert each updated block, selecting ‘re-define block’.

This is just incredibly laborious, open to mistakes, and seems to defy the point of having blocks.