Using XML::XSH2, a wrapper around XML::LibXML: 
open 1.xml ;
cd /dict ;
insert element key prepend . ;
set key[1] 'ADDKEY' ;
my $array := insert chunk '<array><dict/></array>' after key[1] ;
my $key   := insert element key into $array/dict ;
insert text 'SAMPLEKEY' into $key ;
my $array2 := insert element array after $key ;
set $array2/string 'STRING' ;

delete key[last()] ;    
xmove :r string[last()] before preceding-sibling::key[1] ;

save :b ;

[download]
I tried to demonstrate several ways of creating new nodes: via insert and set (more than one node can be created by both, see insert chunk and setting of string).
لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

In reply to Re: Adding Elements to XML by choroba
in thread Adding Elements to XML by techie411

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