Perhaps, alternatively, make it possible to submit a comment to several bug entries at once. So you can write
"Bug #Foo is related to Bug #Bar because both affect the function frob_database in file db.c.
Bug #Foo is also related to Bug #Quux because when fixing #Quux you have to make sure not to make #Foo any worse."
And this will create a shared comment on #Foo, #Bar, #Quux.
Perhaps, alternatively, make it possible to submit a comment to several bug entries at once.
So you can write
"Bug #Foo is related to Bug #Bar because both affect the function frob_database
in file db.c.
Bug #Foo is also related to Bug #Quux because when fixing #Quux you have to
make sure not to make #Foo any worse."
And this will create a shared comment on #Foo, #Bar, #Quux.