Mark Mazower's book Inside Hitler's Greece: The Experience of Occupation,1941-44 gives information on the Italian partisans joining the resistance forces after Italy in September 1943 capitulated and thus ended the Italian part of occupation in Greece.
The Greek edition of the book (pub.Alexandreia) offers info in pages 170-178
p.171 : Mazower mentions that there were 93.000 Italian soldiers stationed in inland Greece and 70.000 in Greek islands.
On 8 September of 1943 there were common celebration by Italian troops and Greek citizens where German forces where not present (p.175) Italians started handing over and selling arms and equipment to Greek resistance forces.
The Germans gave the Italian forces two choices either they keep on fighting under German command or been sent away from Greece. Few choose the first option (10.000 according to Mazower p.177) . The other choice was to actively resist surrender to the German forces. In cases the Italian forces put on a fight to not capitulate to the German forces in Rhodes and the Ionian Islands.
In Kefalonia fighting and the victory of the Germans over the Italians resulted in 155 Italian officers and 4750 Italian soldiers executed.http://en.wikipedia.org/wiki/Massacre_o ... i_Division
Mazower gives a number of 10.000 Italian forces joining Greek resistance in the mountains in April 1944 (p.178)