The ability to create Group Assignments is a great feature because it allows for faster grading as comments, feedback, and grades are visible to the whole team, after the assignment has been graded (no need to copy and paste comments/feedback to every team member).
However, these groups have to be set up ahead of time. In situations where students pick their own partners or when there are team member changes/swaps, Groups Assignments loses its functionality.
My suggestion is to create an option under Group Assignments to allow students to self-select team members. Then when students upload their work, they could tag/add classmates (who are enrolled in the Canvas course) to the submission. When grading, the feedback, rubric comments, and the rating would be transferred over to the other group members.