Andreas,
On 13th october 1943 I/ZG 1 was renamed as I/ZG 26. According to
www.ww2.dk webpage, in october 1943 I/ZG 26 write off 5 Bf 110 due to enemy actions. If some of them were lost before 13th october could be described as I/ZG 1 planes. On Tony Woods webpage, I/ZG 1s crews claims for 14 october are still described as 1., 2. 3,/ZG 1, not 1.;2.; 3/ZG 26, so designation I/ZG 1 could by used for some time longer that 13th october.
II/ZG 1, which stay with this designation until July 1944, according to
www.ww2.dk in october 1943 suffered a loss of 3 Bf 110 to the enemy, and there was no combat losses for II/ZG 1 on november and december 1943.
I'm specially interested in 14th october 1943 because I planned writing an "both side view" article about 2nd Schweinfurt Raid.
Regards,
Szymek