How do I determine wich fule injector is bad, can they be replaced individualy? on 1995 BMW 740i

Also would like to know if there is any harm in running some type of fuel additive to help clean the fuel injectors and will this work?

Asked by for the 1995 BMW 740i
Yes to replacement, need to jump them individually to test.
And how is this accomplished? I would like to determine which is bad and replace it?