No need of WBLOCK or paste an exploded block + redefine it, etc...

This is what the Design Center is for.  Just navigate in it to that "one large drawing" [it will stay there for the next time] and its Block category, and you can bring Blocks in from it without opening it to copy from.  The option of whether to redefine is an added benefit, but I think the avoidance of opening the source drawing is the greater advantage.

What Kent offered to you is using the WBLOCK system that is creating a file with the exact name of the block and with the 0,0,0 located at the insertion point of the block, then you have an "external library" of your blocks..

Then when you insert the file that will become a block inside the file in wich you are working the incoming file/block will update the existing blocks and you will be offered to update it or not by a message like when you explode a block and redefine it inside your file ( that was used in old AutoCAD versions).

An other way would be to use the XREF system but then the files are heavily connected to each other, very sensible to any change of name, location, etc. I wouldn't recommand it if you have a good computer or only if you work with a team...

Hi Kent

Using the design centre and right clicking is a workaround I've discovered, but I tend to copy and paste from one large drawing that contains many blocks that I commonly use - a bit like a autocad reclamation yard. I would just like to know if it's possible to turn this prompt back on somehow when you copy and paste - not sure why they removed it?

I checked my EXPERT level and it is set to (0).

Thank you for your reply. Yes, I do a lot of copying and pasting blocks from diferent files and then edit them slightly to suit the new design. On 2017 a warning prompt would appear everytime I inserted a block to ask if I wanted to redefine it, but now on 2018 it just automatically ignores block definitions. I understand that I can get around it by expoding and re saving as a new block, but often I have blocks within blocks and this becomes unworkable - here's the F2 command list. 

Then it's normal for an incomming block to be as the one already in the file.

Press F2 and read the messages after a copy/paste.

If you want to manage blocks on different files you should use the wblocks or xref or copy/paste an exploded block and "re-block" it whith the same name, insertion point, scale, rotation, etc...

Please tell us if this helped or not.