I have six days academic visit to Germany in August, 6 Days in Prague in September, 15 days in September in Italy, I have been recently granted a 10-month Multiple entries Schengen visa (Type C, with 90 days maximum stay per journey) by the German embassy, valid from Aug 2019.
While applying for this visa with German embassy, I showed them invitation letter from German university as well as the Italian University but I didn't show them the invitation letter from Prague as it came late and I was not sure whether I will be invited at all.
In each journey, I will go from the home and the return home, I mean the itinerary will be H--G--H, H--P-H, H-I-H, H=Home, G=Germany, P=Prague, I=Italy.
(1) Is that a problem that I didn't apply for a visa with the Italian embassy as I am staying the maximum number of days there.
(2) Is that a problem that I didn't submit an invitation letter from Prague to the German embassy?