At, re combining the French & English editions - yes, if they are both one book each ie the French one isn't split into 2 or more books. The French do that often and if you come across that, don't combine.
The term you are looking for is combining. Merging means you end up deleting one edition and you don't want to lose one in this case.
As to the author names, Richard Kirk should be in first author spot, on all editions, so you can combine them. Robert Holdstock should be in the second author spot on the French editions as they were published under that name in that country.
The term you are looking for is combining. Merging means you end up deleting one edition and you don't want to lose one in this case.
As to the author names, Richard Kirk should be in first author spot, on all editions, so you can combine them. Robert Holdstock should be in the second author spot on the French editions as they were published under that name in that country.