If the second one "overrides" the first, then I am guessing that the values can be NULL.
Try this set
statement:
SET MI.M_Reps_Contact_Info = COALESCE(M.Other_EE_Names + ' ', '') +
COALESCE(M.Other_EEs, '') +
COALESCE(MI.M_Reps_Contact_Info +
CHAR(13) + CHAR(10), '' )