Where do i go??????????????????????

i am traveling from canada to munic to romania amnd from the first half of teh trip ( canada to munich) i am traveling with lufthansa opaarated by air canada so air canada but in the second half ( munich to romania) i am travelling operated by lufthansa sicne i bought my tickets online i have to call them to tell them that im still going do i call both air lines or just air canada? and whos bagage allowence do i follow because they are different sicen i bought my tickets before june 1st lufthansa only lets me have a baggage of 20 kg while air canada 23kg? thx