Moving students to another grouping - Assignments grades issue

Hi,

We have issues when moving a student from a grouping to another grouping. The scenario is like this:

• Students A is in Group X and Grouping X 
  
• Did assignment 1 in Group X and got 80%
• Then, need to move to to Group Y
• In Group Y, did Assignment 2 in Group Y and got grade 70%

Now the issue is other students in Group Y has done only 1 assignment (Assignment 2) but student A has done 2 assignments and system has captured her score total based on 2 assignments. The other students grade are based on 1 assignment.

Assignment 1 grade is still in the gradebook for Student A.

1. How do I remove Assignment 1 grade from gradebook?
   
2. How does moving groups/grouping affects students total grades?

Please advise.

TQ