This is a feature I would dearly love to see added to editing BASIC programs!
As I normally use SBASIC (as opposed to SuperBASIC), when I want to block copy code I either load the program into a text editor (saved programs are basically just plain text), or save the block of code to be copied to a ramdisc, load it into an SBASIC job, renumber it there, save again, then merge with the original program.
Very clumsy, but once you've done it a few times, it just becomes normal.
e.g. LOAD mybigprogram_bas
SAVE ram1_tmp_bas;line1 TO line2 (line number range to be copied)
SBASIC
LOAD ram1_TMP_bas (into the new SBASIC)
RENUM as required
SAVE ram1_TMP_bas
switch back to original BASIC program
MERGE ram1_tmp_bas
It looks long winded and clumsy, I know. I've just got so used to doing this over the years I don't give it a second thought.
Not tried this on Minerva MultiBASIC, don't know if it would work on that.
Another approach might be to learn to use Tim Swenson's SSB (Structured Super BASIC)
https://dilwyn.theqlforum.com/program/index.html. It allows you to write QL BASIC programs without line numbers using an editor, making it very easy to do things like copying blocks and other things not so easy to do in standard QL BASIC. Probably the nearest thing we have to an IDE (Integrated Development Environment) for developing QL BASIC programs.
Might also be useful for you to look at the MasterBasic software, originally from Ergon Development, now available as freeware. It's been a while since I last used it, but I remember it being very useful when writing BASIC programs.
https://dilwyn.theqlforum.com/program/mbs151d.zip