It is very similar to time card entry. I looked at ABC Tracking In/Out Time.You would need 2 tables.
Table 1
Project Stage - Each record is a record for every project stage.
Project A Stage 1
Project A Stage 2 and so on
Table 2
Time Entry - this is where you are now keeping the log of changes.
Each Project has many Project Stages
Each Project Stage has many Time Entries
Even though you are adding another table and more data it is simplifying the data.
Sorry I don't have the time to develop an example to use but the app Kirk Trachy has called ABC Tracking In/Out Time will put you on the right path I believe.
