my 2cents
1. Main - QA - IT - dev1-bug1
- dev2-bug2
- dev3-bug3
- dev4-bug4
2. Before performing merge, do merge back first.
3. Lable all releases
4. Merging, dev to IT may or may not controlled. But IT - QA, QA - main must be controlled.
5. For every MR, you may start a new one.