Coming back after a milestone is done

[JP-droidic]

Hi team,

I’m looking for advice from people who’ve been using GSD for a long time on how you handle the following cases:
1. Changes after a milestone is complete
A milestone has been delivered and it included, say, seven phases. The client comes back with enhancements that may require changes to work done in (for example) phase 3 and phase 5. Would you create a brand-new phase/milestone for this, or reopen/update the original phases somehow?
2. Issues on a project that wasn’t originally built in GSD
If a client brings a list of issues spanning the whole system on a project that wasn’t created via GSD, do you treat that the same way—i.e., create a new milestone and capture everything there as work to be done?
3. Continuous improvement and organisation
How do you manage continuous improvements over time? If each new batch of features becomes a new milestone, what’s the best way to keep things organised and easy to reference later? For example: renaming phases to be more descriptive, archiving/hiding old phases, or another structure that works well in practice.

Thanks in advance.